Semiconductor compounds based on metal chalcogenides are used in opto- and nanoelectronics and sensorics, devices for energy conversion and storage, and biomedicine. To obtain them, both physical (vacuum deposition, thermal evaporation, magnetron sputtering) and chemical (spray pyrodysis, SILAR method, electrochemical and chemical deposition) methods of preparation are used. Chemical deposition is the most instrumented, low-temperature method that does not require aggressive media and ensures reproducibility. Obtaining one of the most popular representatives of a widespread family of semiconductors, narrow-gap PbS, thiourea N2H4CS(TM), thioacetates CH3CSNH2 (TAA) and allylthiourea C4H8N2S (ALM) are used as a donor of sulfur ions S2-. Each sulfidizer is characterized by its own rate of formation of a thin-film layer of lead sulfide. Knowledge of the mechanism is required to control the formation of PbS films. We have considered two fundamentally different mechanisms of the formation of metal sulfides. To predict the conditions for the formation of lead sulfide, an analysis of ionic equilibria was carried out in this work, with the determination of the concentration regions of the formation of films of lead sulfide in three reaction systems «Pb(СН3СОО)2 - Na3C5Н5О7 - NH4OH - TM», «Pb(СН3СОО)2 - Na3C5Н5О7 - NаOH - TАА», «Pb(СН3СОО)2 - Na3C5Н5О7 - КOH - АTM». The work discusses the results of experimental verification of the calculated conditions for the chemical deposition of PbS films on glass substrates. Electron microscopic studies and EDX analysis have shown the effect of the nature of the chalcogenizer on the thickness, morphology, elemental composition, as well as on the size and shape of grains from which synthesized PbS films are formed from the above reaction systems.