Energy consumption is one of the most crucial design issues in wireless sensor networks since prolonging the network lifetime depends on the efficient management of sensing node energy resource. In this research study, a new TDMA based MAC protocol, which is not only energy aware but also delay sensitive, is introduced for wireless sensor networks. In the proposed MAC, to achieve energy conservation, sensing nodes employing the proposed MAC sleeps periodically to reduce duty cycle and minimize idle listening. In addition, to provide lower message delay, any time critical sensing node requests extra time slots form the central node when its queue size exceeds the upper threshold value. Unlike common wireless sensor network models with a multi-hop topology, the proposed WSN architecture has a centralized structure especially for energy efficiency and fulfillment of the delay requirement of time critical networking applications. The proposed MAC has been modeled and simulated using OPNET Modeler Software for performance evaluation. Simulation results of the WSN model employing the new MAC are also presented including comparisons with those of a WSN counterpart employing conventional IEEE 802.11 DCF MAC protocol. By varying the interarrival time between 1 and 8 s for 100 wireless sensing nodes, in the best case, as a consequence of the new scheduling algorithms developed 9448 times better end to end message delay result and 1.9 times lower energy consumption ratio have been obtained for WSN employing the proposed MAC when compared with the WSN model employing IEEE 802.11 DCF MAC. (C) 2007 Elsevier B.V. All rights reserved.