When Hydro starts its operations – in Norway – factories, railways, ferries and power plants are built. In addition, entire urban communities are created. The company builds homes for their employees, to some extent in Notodden and even more so in Rjukan. Here Hydro also takes responsibility for many of the institutions considered public services today – including the operation of hospitals.

On 21 April 1917 five men meet in Berlin and establish "Vereinigte Aluminium-Werke Aktiengesellschaft". In the 1920s, the company implements the first social programs for its employees, including retirement pension and housing.

Loaded with experience from the building of Notodden and Rjukan, Sigurd Kloumann assumes responsibility for power plants, smelters and local communities in Høyanger, Norway. The plant later becomes part of ÅSV and finally Hydro. The vision is to build a green industrial city, with parks, avenues, houses and gardens, providing good living conditions for everyone. Høyanger becomes a spearhead in the development of the Norwegian welfare state.

Despite the fact that Rjukan is located between high mountains, the city residents should be able to see the sun during the winter months. So Hydro constructs a gondola lift from the valley up to the top of the mountain. Everyone is allowed to use the Krossobane and tickets cost two cents - right up until the 1970s. The cable-way is still a popular attraction today.

After a decade of wage cuts, Norwegian employers demand an additional 15 percent reduction during labor negotiations. The result is a conflict and a lockout by the employers. At Hydro's terminal in Menstad, non-union employees continue working. Unionized workers take action, and police and military forces are deployed to restore order. The conflict has become the Norwegian symbol of labor unrest in the "dirty thirties."

"The dirty thirties" are at their worst when Hydro lets 400 employees go in Notodden. Production is temporarily halted and many workers are transferred to Porsgrunn. One of the countermeasures is to move the company's sack production from Oslo to Notodden. This creates 100 new jobs in the short term. New initiatives follow later.

Hydro is involved in the construction of German-owned Nordag's aluminium and magnesium projects at Herøya in Porsgrunn. Prisoners of war are conscripted into the construction of plants which are bombed by the U.S. Air Force. Fifty-five lives are lost and further progress in the projects is stopped. Prisoners of war are also used to build Hydro's power station in Mår in Telemark county and when German authorities build the aluminium plant in Årdal.

Hydro and the union local at Herøya enter into a productivity agreement to strengthen efficiency, effectiveness and cost-consciousness. This cooperation agreement is initiated in several factories. Training is combined with theory and practical training that leads to an apprenticeship certificate and makes Hydro into a corporate pioneer. Relations between management and the workers are improved, while the number of employees actually drops.

Hydro participates in Mineração Rio do Norte S.A., MRN, in Brazil, holding five percent in the bauxite mine located in Trombetas in the State of Pará. The region is partly populated by the Quilombolos, an indigenous people descending from former slaves of African origin. After the agreement with Vale in 2011, Hydro will also process Vale's share of the MRN production, 40 percent of the total annual production of approximately 16 million tonnes.

The state-owned aluminium company ÅSV and Hydro's aluminium business merge. Hydro owns 70 percent of the shares in the new company and buys the remainder in 1988. ÅSV aluminium plants have lower productivity than Hydro's prior to the merger. This is the start of a series of efficiency measures and job cuts, culminating in 1991 with about 1 000 fewer jobs, shared between 400 in Årdal, 350 in Sunndal, 200 in Karmøy and 100 fewer in Høyanger.

The plan is to develop a bauxite mine and an alumina refinery in a remote area also inhabited by indigenous Khonds. The project turns out to be very complex including conflicting interests between national and local politics, extensive bureaucracy and a cross-section of NGOs with various agendas. Hydro withdraws from the project in 2002, following the fatal shooting by the local police of three men in a nearby village.

Hydro establishes ethical guidelines applicable to all employees. These cover, among other things, questions about integrity (including gifts and other benefits), conflicts of interest, personal conduct and the handling of confidential information.

The Dow Jones Sustainability Indexes are created. Many perceive these to be the world's most prestigious sustainability indexes. Hydro has earned a place right from the first year.

Hydro acquires a 34 percent share in the alumina refinery Alunorte in Barcarena, Pará in Brazil. Following three expansions, Alunorte is by 2008 the world’s largest alumina refinery. Hydro helps develop Alunorte’s education and sports program, where kids are inspired to take school seriously in order to qualify for Alunorte Rain Forest - the football team travelling every year to the Norway Cup, the world’s largest youth soccer tournament.

Hydro acquires Wells Aluminum Corp., a major extrusion company with seven plants in six states in the U.S. The business includes a foundry that produces extrusion ingot.

After 50 years as a producer of magnesium Hydro finds it necessary to close these plants in Norway and Canada. The reaction is strong. Transition measures include severance packages, support for new startups and job relocation counseling. After some time, the restructuring in Porsgrunn is hailed as a success story. Many new, future-oriented jobs are created and experience gained here comes in handy later in several places e.g. in the UK, Germany and Norway.

Rock fill removed during the construction of the new Tyin power plant is used to improve the national highway over the Tyin mountain in cooperation with the National Roads Administration. The improvement leads to increased uptime for the highway during the winter. Together with the municipality of Årdal, a tourist trail is created and a new water supply to Årdal is built. The project is implemented in dialogue with local residents.

An assessment is completed of the impacts on the environment and society arising from the construction of the Qatalum aluminium plant in Qatar. The assessment is communicated to the local population through supplements distributed with newspapers and public meetings.

Hydro initiates an extensive investigation into allegations of corruption in Libya in the early 2000s. The case, which comes up in connection with the merger of Hydro's oil and gas activities with Statoil, receives a lot of attention. The National Authority for Investigation and Prosecution of Economic and Environmental Crime in Norway (ØKOKRIM) decides in May 2009 not to initiate a criminal investigation into the case.

The cornerstone of the new Qatalum aluminium plant in Qatar is laid. Hydro owns 50 percent and has been responsible for the project. At the peak there are more than 20 000 workers on the construction site. Almost all are migrant workers and the project builds its own village with space for 10 000 workers. The village sets a new standard for accommodation of workers in Qatar.

Qatalum starts production from the new aluminium plant in Qatar. Hydro, which owns 50 percent of the plant, receives criticism from some quarters for the working conditions in Qatar. This includes that the country does not allow freedom of association for migrant workers.

Hydro acquires most of Vale’s aluminium assets in Brazil. This includes 60 percent of the Paragominas bauxite mine, increasing to full ownership by 2015. In addition, Hydro becomes majority-owner in Alunorte, the aluminium smelter Albras and the planned alumina refinery CAP. Some 3 600 employees and 1 500 contractor-employees join Hydro.