Perovskite solar cells (PSС) attracted much attention due to their excellent optoelectronic characteristics and efficiency reached 24.2% only in the last few years. Despite their high efficiency, there is still a limited stability of the PSC, which must be overcome. It was recognized that a humid environment and oxygen is the main problem in the decomposition of perovskite materials. This article is devoted to the study of the perovskite thin films stability by treating the surface with pyridine. Perovskite samples were studied by UV-Vis spectroscopy as well as FTIR spectroscopy. FTIR indicated a slight change in the structure of perovskite films. While no damage under the action of pyridine was detected, the material retained its semiconductor properties. It is concluded that increasing the long-term stability of organo-inorganic perovskites requires further research.