Formation of phase composition and structure is investigated in nanoscale CoSb$_{x}$ (30 nm) (1.82 $\leq$ х $\leq$ 4.16) films deposited by the method of molecular-beam epitaxy on the substrates of the oxidized monocrystalline silicon at room temperature and 200°C with subsequent thermal treatment in a vacuum within the temperature range of 300—700°C. As determined, the films after the deposition are in amorphous state on cold substrate and in polycrystalline one without texture on heated substrate. Crystallization of amorphous CoSb$_{x}$ films occurs at heating within the temperature range of $\cong$ 140—200°C. In films with higher Sb content, the temperature range of crystallization increases and is shifted to the side of higher temperature. Intensive process of evaporation of excessive Sb and Sb from antimonides is observed at annealing of X-ray amorphous films above 300°C and at annealing of polycrystalline films above 450—500°C. It leads to increase in amount of the CoSb and CoSb$_{2}$ phases and to decrease in CoSb$_{3}$ content.