The aim of this work was to determine the agents that allow epoxy mortars to harden at a low temperature (below 10 degrees C.) and a high relative humidity (100%). Polish made epoxy resin Epidian 1:5 and the following hardeners were applied: ethylbiamine, triethylenetetramine and their adducts with the above resin. Resins solubility and the rate of solutions gelation were evaluated. Next, hardening agents in unfavourable conditions were examined and finally, physical and mechanical properties of mortars were tested. Results are: 1) Epoxy resin solutions in aromatic hydrocarbons are not suitable for application in the practice because of a poor reticulation capacity. Good results were obtained for alcohol solution of Epidian 5 hardened with triethylenetetramine. 2) At a constant solution to aggregate ratio (1:10), it has been found out that the properties of mortars depend on solution concentration as well as on type and granulation of aggregate. At a maximal concentration, mortars of the highest mechanical resistance and minimum absorption capacity are obtained. However the increase of aggregate granulation causes a decrease of the absorption and resistance features of mortars. 3) Each type of aggregate is characterized by a specific value of binder uptake (Tables 11, 12). The excess of binder accumulates on the surface of mortar forming a glittering film. A lower binder quantity results in a decrease in mortars resistance. It is advisible to use less binder, by 10-10%, thn it has been indicated by the binder uptake of aggregate. 4) When applying a resin in a quantity according to the binder absorption of aggregate the conclusion from tables 19-22 has been confirmed. It has been observed that the binder absorption decreases, the resistance drops rapidly while the absorption of liquids increases with the increase of granulation. A decrease of water resistance is also noticed. If the ratio of aggregate to resin quantity exceeds 15:1, the resistance drops by 50-70%. If below this value, it ranges from 20 t0 40%. The degree of consolidation is also decisive for mortar properties. The higher the apparent density, the higher the resistance is. 5) Epoxy mortars show a considerably higher resistance to the action of water soluble salts than natural stone, which is connected to their hydrophobic properties. In spite of this, the rate of water rise is rather low and, after a certain time, water nearly fills up the open pores of mortar. 6) All the mortars that contain more than 10 parts of aggregate per one part of resin are light-resistant. In order to obtain light-resistant mortars, it is necessary to prevent a deposit of a resin film on the surface, or to remove it if it has already been formed.