We investigated the effect of oxygen partial pressure pO2 during melt‐and‐solidification heat treatment on the superconducting properties of grain oriented Bi‐2212 thick films. Tc and c‐axis parameter decreased with increasing pO2, indicating the samples were in the over‐doped state. The heat treatment temperature which gave highest Jc increased with increasing pO2. This was explained by the increase of the solidification temperature of Bi‐2212 with pO2. Both the resistive Jc and intergrain Jc estimated from the dc magnetization increased with increasing pO2 when the samples were melt‐solidified under an optimum condition for each pO2. Amplitude dependence of ac susceptibility suggested that the coupling of Bi‐2212 grains was improved with increasing pO2. Irreversibility field Birr below ∼60 K was also enhanced with increasing pO2. Low temperature annealing under high pO2 after the melt‐solidification also increased the oxygen content in Bi‐2212 and hence Birr. However, the annealing did not change the amplitude dependence of ac susceptibility, and transport Jc at 4.2 K was almost independent of the annealing. The results indicate that the increase of Jc at 4.2 K with increasing pO2 during melt‐solidification is primarily attributed to the improvement of the grain couplings. © 1996 American Institute of Physics.