Abstract We performed electrical resistivity and X-ray diffraction measurements on the BiS 2 -based compound, EuSr 2 Bi 2 S 2.5 Se 1.5 F 4 , under high pressure using cubic and diamond anvil cells, respectively. We have also measured electrical resistivity at low temperatures and ambient pressures. The superconducting transition temperature ( T c ) was 1.13 K at ambient pressure and EuSr 2 Bi 2 S 2.5 Se 1.5 F 4 was found to behave like a superconductor. Upon the application of increased pressure, T c increased and then decreased again, which was attributed to the structural phase transitions that accompany increased pressure in EuSr 2 Bi 2 S 2.5 Se 1.5 F 4 superconductors.