Domain wall motion was directly observed at temperatures near to the monoclinic-to-tetragonal phase transition temperature (TM-T) in -oriented 0.23Pb(In1/2Nb1/2)O3-0. 42Pb(Mg1/3Nb2/3)O3-0.35PbTiO3 (0.23PIN-0.42PMN-0.35PT) single crystals using a polarizing light microscope, and evident 90°and 180°domain switches were observed near the Curie temperature (TC). Two dielectric loss anomalies were observed at temperatures near TM-T in the -oriented PIN-PMN-PT single crystals, while an additional dielectric loss peak was found at temperatures a few degrees below TC, which was associated with domain wall motion. Based on the domain structure observations, a domain switching mechanism was proposed to explain the novel dielectric loss peak at several degrees below TC. 2013 The Royal Society of Chemistry.