In this paper, we present an Energy-efficient Mobile Group Clustering (EMGC) protocol that supports group mobility and a group handover scheme. The mobile sensor nodes are divided into three categories, namely cluster heads, group leaders and group members. In our cluster formation and group handover scheme, group leaders and cluster heads do most of the communications to save on energy consumption during which group members are placed in the sleep condition. This scheme will reduce the number of control packets and frequent topology changes in the networks. Simulation results show that the EMGC protocol outperforms MN-LEACH, GMAC, MBC protocols in terms of energy dissipation and the number of data items received at a base station.