We report the observations of Electrostatic Solitary Waves (ESWs) associated with reconnection by the Wideband Plasma Wave Receiver of Cluster and the Wave From Captures of Geotail near the diffusion region at dayside magnetopause and in the magnetotail region. ESWs have been observed along the plasma sheet boundary and near diffusion region, both earthward and tailward of the x-line. Cluster II detected the ESWs simultaneously at both side of neutral sheet by three of the four satellites. By carefully checking the data of particle, field and wave, we studied the temporal and spatial evolution of ESWs, their relative locations with reconnection layer and the relationship with the distributions of electrons. Comparison with full particle simulations with the observations, we discuss the importance of these solitary waves in collisionless reconnection and their possible generation mechanisms is provided. (c) 2005 COSPAR. Published by Elsevier Ltd. All rights reserved.