An energy efficient conversion of ethane to ethylene involving simultaneous oxidative conversion (which is exothermic) and thermal cracking (which is endothermic) reactions of ethane in the presence of steam (steam/C2H6 mol ratio = 1.0) and limited O-2 (C2H6/O-2 mol ratio greater than or equal to 4.0) over a BaO-promoted La2O3 supported on low surface area macroporous silica-alumina commercial catalyst carrier has been thoroughly investigated, influence of various process parameters such as temperature (700-850 degreesC), C2H6/O-2 feed ratio (4.0-8.0) and space velocity (50,000-200,000 cm(3) g(-1) h(-1)) on the conversion, product selectivity and net heat of reactions in the process has also been studied. At all the process conditions, there was no coke deposition on the catalyst. High selectivity(greater than or equal to 85%) for C2+ olefins (at 50-60% conversion) can be obtained in the process at a low contact time (<10 ms), particularly for the higher C2H6/O-2 ratios ( 6.0) and temperatures (greater than or equal to 800 degreesC). The process exothermicity is decreased appreciably with increasing the temperature and/ or the C2H6/O-2 ratio. The net heat of reaction in the process can be controlled by manipulating the C2H6/O-2 ratio and reaction temperature. Also, because of simultaneously occurring endothermic and exothermic reactions, the process is highly energy efficient and non-hazardous.