A fundamental problem that confronts future applications of sensor networks is how to efficiently locate the sensor node that stores a particular data item. It is known that distributed hash table (DHT) based Internet peer-to-peer (P2P) protocols provide near-optimum data lookup times for queries made on networks of distributed nodes [2, 23-25]. A generic mapping of these protocols to sensor networks is, however, perceived as difficult [1]. We present a novel DHT based network protocol for sensor networks — Chord for Sensor Networks (CSN) — for which bounded times for data lookup, in the order of O(logN) messages, can be achieved in an energy efficient manner. CSN makes system lifetime of the sensor network proportional to its effective use. Furthermore, CSN scales well to large-scale sensor networks when the information about other nodes logarithmically increases with an increase in the number of sensor nodes.