Hermaszewski died in a Warsaw hospital on Monday afternoon, a Polish MEP Ryszard Czarnecki, Hermaszewski's son-in-law, told PAP.
As PAP found out unofficially, the general suffered from kidney disease, he was operated on on Monday, but there were complications that led to his death.
A Polish military pilot, Hermaszewski, took part in a manned space flight for the USSR on June 27, 1978. His space trip lasted nearly eight days.
During the flight aboard Soyuz-30, together with Russian cosmonauts Hermaszewski took part in scientific experiments in the field of space biology and medicine. An experiment on semi-conductors has been applied in works on space materials technology.
He was the world's 89th cosmonaut. (PAP)