Hermaszewski passed away on Monday afternoon in a Warsaw hospital, Polish state news agency PAP reported.
News of his death was announced by his son-in-law Ryszard Czarnecki, a well-known conservative politician.
According to unofficial reports, Hermaszewski died from complications after a kidney operation.
Hermaszewski was born in 1941 in the Volhynia region of present-day Ukraine. After World War II, his family moved to the town of Wołów, near Wrocław in southwestern Poland, where Hermaszewski went to primary and secondary school.
After finishing a school for military pilots in the eastern town of Dęblin as the highest ranked graduate in 1965, he first served in the air defence regiment in the western city of Poznań.
In 1967, Hermaszewski graduated with honours from the Academy of the General Staff in Warsaw.
In 1976, he was selected from among 500 pilots to participate in the Soviet Union’s Intercosmos programme.
A member of Intercosmos’ second mission, Hermaszewski travelled into space on June 27, 1978, alongside Soviet commander Pyotr Klimuk, aboard the Soyuz 30 spacecraft.
During the mission, Hermaszewski conducted scientific experiments and photographed Earth’s surface from the space station Salyut 6.
He spent close to eight days in space before the team returned to Earth on July 5, 1978, landing in the steppes of then-Soviet Kazakhstan, some 300 kilometres west of the city of Tselinograd, now Astana.
Hermaszewski flew his farewell flight, on a MiG-29 fighter jet, at the age of 64 in October 2005.
Afterwards he continued to tour the country, telling audiences about his space mission and promoting astronautics.
In 2011, fifty years after Yuri Gagarin became the first man to fly in space, Hermaszewski was among the cosmonauts decorated by the then Russian President Dmitry Medvedev “for services to the conquest of space.”
His son-in-law took to Twitter on Monday evening to pay tribute to “the first Polish cosmonaut, a brilliant pilot, a good husband and father, a beloved grandfather.”
(pm/gs)
Source: PAP, wp.pl, rp.pl, rmf24.pl
Click on the audio player above for a report by Radio Poland's Agnieszka Łaszczuk.