Experimental data on the evaporation of chondrule melts, compositions of which correspond to those of chondrules from the Saratov chondrite, were obtained by the Knudsen effusion mass spectrometric method. The partial pressures of vapor species over the chondrule melt in dependence on the temperature and evaporation time were determined. During chondrule evaporation, alkalis were observed in the gas phase at 1300–1600 K. The p(K) and p(Na) were in the range of 10–8–10–7 atm at 1450–1500 K. Evaluation of the p(K) / p(Na) ratio was ~ 0.57, which confirms the observation of greater volatility of Na2O compared to K2O during evaporation of chondrule melts. The calculations of oxide activity coefficients in the K2O–Na2O–SiO2 melts and in the chondrule melts showed that the K2O and Na2O activity coefficients monotonically decrease with an increase of SiO2 content in the melt.