What materials were used to make pennies before 1982?

From mid-1864 to 1942 and from 1944 to mid-1982, US cents were struck in a bronze alloy consisting of 95% copper and varying fractions of tin and/or zinc.

1943 cents of course were struck in zinc-plated steel because of wartime copper shortages.

Compositions varied before 1864. Small cents were generally struck in an alloy of 88% copper and 12% nickel, while large cents were made of pure copper.