Oxidative dehydrogenation of ethane to ethylene in presence of steam (steam/C2H6 mole ratio = 1.0) and limited O-2 (C2H6/O-2 mole ratio greater than or equal to 4.0) over a SrO-promoted Sm2O3, supported on low surface area macroporous silica-alumina commercial catalyst carrier (SA5205, obtained from Norton Co. USA) has been thoroughly investigated. Effect of different process parameters such as temperature (700-850degreesC); C2H6/O-2 feed ratio (4.0-8.0) and gas hourly space velocity (5x10(4)-20x10(4) cm(3)g(-1)h(-1)) on the conversion of ethane and product selectivity in the process has been studied. High selectivity (greater than or equal to80%) of C2+ olefins at 50-70% conversion of ethane could be obtained at very low contact time without coke deposition on the catalyst at 800-850degreesC.