Abstract: The review deals with the development of a process for preparing cobalt catalysts for hydroformylation and carboalkoxylation. Common term oxo synthesis is used for these reactions. Theoretical principles of the classical synthesis of cobalt carbonyls are discussed, and the main directions of the modern development of oxo synthesis are considered. Much attention is paid to carboalkoxylation catalysts based on cobalt carbonyl complexes. The use of nitrogen bases as promoters of ethylene carboalkoxylation catalysts and the use of cobalt carbonyls on an inorganic support are analyzed. An approach to solving the problem of recycling oxo synthesis catalysts, alternative to heterogeneous catalysis, namely, thermoregulated phase-transfer cobalt catalysis, is described.