The IEEE 802.11 standards support the peer-to-peer mode Independent Basic Service Set (IBSS), which is an ad hoc network with all its stations within each other?s transmission range. In an IBSS, it is important that all stations are synchronized to common clock. Synchronization is needed for frequency hopping and power saving. The synchronization mechanism specified in the IEEE 802.11 standards has severe scalability problem. The probability that stations may get out of synchronization is pretty high in large IBSS. New synchronization algorithm has been proposed for large-scale ad hoc network. We propose more efficient algorithm in this paper that synchronizes clock more accurately. We are able to synchronize the clock within 100 ?s when the number of stations is more than 300. This is a big improvement over the current best algorithm and the 802.11 specified protocol. To our best knowledge, the current best algorithm can synchronize the clock within 550 ?s for 300-station network. The 802.11 standard protocol can have clock drift over 5000 ?s for the same network.