In 1947 the country decided to rebuild its infrastructure and re-opened the local chemical plant which manufactured explosive materials in 1947.

A significant increase in the sporting level took place in the mid-1970s after the club's name was changed to BKS Chemik, incorporated into the parent multi-sports club which base was expanded to include a football stadium in Wyżyny along with a training ground complex.

In 1979, to celebrate the promotion of Chemik to the second tier, a friendly match was played with the West German club FC Oberrot, which was won 8–0.

In the 1991–92 season, they reached the highest league pyramid position in the club's history, 5th in the second tier.

The merger turned out to be very unsuccessful, and the Zawisza's senior side started anew from the bottom of the league pyramid, with the senior merged side reverting to "Chemik", leaving the reserve team in the fifth division, which subsequently became Zawisza's senior team.