Recently, a rapid growth in various applications of ejector refrigeration systems has been observed in numerous sectors. With the applications based on solar or waste energy, designed to supply the motive energy have becoming widespread, a real alternative to compression devices in air-conditioning technologies has become a fact. Furthermore, it has been shown that ejector systems may effectively compete with absorption systems under temperature of the motive heat source lower than 80 degrees C. This paper presents experimental investigations carried out on a specially constructed prototype/stand for the ejector air-conditioning, operating with isobutane as a working fluid under motive vapour temperature below 75 degrees C The effects of operation parameters have been thoroughly analysed. The ejector cycle performance coefficient was presented and discussed. The loss coefficient for the ejector was determined as well. It has been shown that loss coefficient in the investigated set-up is higher than 0.75. (C) 2014 Elsevier B.V. All rights reserved.