In present work, the effect of Pb1-xSnxTe < In> (111) surface chemical treatment on electrophysical and optical properties was studied. It was shown that treatment of Pb1-xSnxTe < In> (111) surface in HCl-isopropanol (HCliPA) solution led to removal of native oxides and surface enrichment by elemental tellurium of several nm thickness. Subsequent anneals in vacuum led to desorption of elemental tellurium and revealing (1x1) surface structure. We present angle resolved photoemission spectroscopy (ARPES) measurements of the surface states on chemically prepared (111) oriented MBE-grown films of Pb1-xSnxTe, a three-dimensional topological crystalline insulator (TCI). The surface states with Dirac-like dispersion at Γ in the surface Brillouin zone were detected. The dark current and photocurrent were found in strong dependence on the surface chemical procedure and composition. The relative simplicity of the preparation technique is encouraging, and suggests a clear path for future investigations of TCI states on alternative surface orientations in (Pb,Sn)Te solid solutions and applied aspects of TCI research.