Abstract The article is devoted to the development of dry masonry mixes with hollow ceramic microspheres for winter masonry works. For the single-layer external structures made of effective piece elements, it is necessary to use the “warm” masonry mortars. The existing masonry mortars with traditional light-weight fillers have low grade strength, and their do not gain the minimum required strength at hardening at low temperatures. The use of hollow ceramic microspheres as a light-weight filler allows us to obtain an effective mortar with the required characteristics, providing a high coefficient of heat homogeneity of external structures. The optimum compositions of the mortars with hollow ceramic microspheres for the use at subzero temperatures were obtained. The effects of various antifreeze additives and their complexes on physical, mechanical and technological properties of masonry mortars as well as their resistance to the efflorescence were studied.