CuInSe2/CdS/ZnO and CuInGaSe2/CdS/ZnO heterojunction solar cells have been prepared and the Raman scattering spectra from the interface between CdS buffer and CIS absorber layer have been measured as a function of hydrostatic pressure. CuInSe2 absorber layers were prepared by the metal organic chemical vapour deposition (MOCVD) technique on Mo coated soda lime glass. The CdS buffer layer and ZnO window layer were deposited by chemical bath deposition (CBD) and R. F. magnetron sputtering, respectively. The pressure coefficient of the A1(Γ1) peak of the CIS layer in the solar cell was measured to be , slightly smaller than the value obtained for a thin film of CIS only, which was . The measured pressure coefficient of the A1(Γ1) peak of the CdS layer in the solar cell, , is much larger than that obtained with the CdS thin film grown on a GaAs substrate, which was . The pressure coefficient of the A1(Γ1) peak in the CuIn0.7Ga0.3Se2 thin film is , which is lower than that of the CuInSe2 thin film.