We characterized the surface morphology of (110) thin films of 214‐type superconductors epitaxially grown on substrates of 214‐type materials with various degrees of lattice mismatch. By reactive co‐evaporation, (110) thin films of La1.85Sr0.15CuO4and Pr1.85Ce0.15CuO4are grown on (110) substrates of La2CuO4and Pr2CuO4. Reflection high energy electron diffraction, scanning electron microscopy, and atomic force microscopy show the roughness of the film surface is reduced by decreasing mismatch. The surface roughness of La1.85Sr0.15CuO4(110) thin films on La2CuO4substrates is comparably small to that of (001) films on SrTiO3(001) substrates. ©1995 American Institute of Physics.