Designs of various types of intermediate coolers of multistage ejectors are analyzed and thermal effectiveness and gas-dynamic resistance of coolers are estimated. Data on quantity of steam condensed from steam-air mixture in stage I of an ejector cooler was obtained on the basis of experimental results. It is established that the amount of steam condensed in the cooler constitutes 0.6–0.7 and is almost independent of operating steam pressure (and, consequently, of steam flow) and air amount in steam-air mixture. It is suggested to estimate the amount of condensed steam in a cooler of stage I based on comparison of computed and experimental characteristics of stage II. Computation taking this hypothesis for main types of mass produced multistage ejectors into account shows that 0.60–0.85 of steam amount should be condensed in stage I of the cooler. For ejectors with “pipe-in-pipe” type coolers (EPO-3-200) and helical coolers (EO-30), amount of condensed steam may reach 0.93–0.98. Estimation of gas-dynamic resistance of coolers shows that resistance from steam side in coolers with built-in and remote pipe bundle constitutes 100–300 Pa. Gas-dynamic resistance of “pipe-in-pipe” and helical type coolers is significantly higher (3–6 times) compared with pipe bundle. However, performance by “dry” (atmospheric) air is higher for ejectors with relatively high gas-dynamic resistance of coolers than those with low resistance at approximately equal operating flow values of ejectors. Keywords: ejector, stage, cooler, characteristics, condensation, pressure losses