Light S.A. (Portuguese pronunciation: [ˈlajtʃ]) is a private sector public utility company of Rio de Janeiro, Brazil.

Founded in 1904 in Toronto, Ontario, Canada by The Rio de Janeiro Tramway, Light and Power Co. Ltd., it was authorized to operate in Brazil in 1905.

Research activities of generation, distribution and sale of electricity and each of these areas is represented by a different company.

Currently the controlling stake in Light is owned by CEMIG, an electric company based in Belo Horizonte.

Electrical power infrastructure in Rio de Janeiro was originally developed in 1904 by the Rio de Janeiro Tramway, Light and Power Company, a company financed with foreign capital and legally domiciled in Toronto, Ontario, Canada.