  The cosmic-ray hydrogen and helium ($^1$H, $^2$H, $^3$He, $^4$He) isotopic
composition has been measured with the satellite-borne experiment PAMELA, which
was launched into low-Earth orbit on-board the Resurs-DK1 satellite on June
15th 2006. The rare isotopes $^2$H and $^3$He in cosmic rays are believed to
originate mainly from the interaction of high energy protons and helium with
the galactic interstellar medium. The isotopic composition was measured between
100 and 1100 MeV/n for hydrogen and between 100 and 1400 MeV/n for helium
isotopes using two different detector systems over the 23rd solar minimum from
July 2006 to December 2007.
