Magnetic properties of the solid solution orthotitanate Ce 1؊x Nd x TiO 3 have been studied, where the characteristic susceptibility peaks are found in their susceptibility}temperature ( }T) curves as in La 1؊x Sm x TiO 3 and Pr 1؊x Nd x TiO 3 . The common features of this phenomenon are the pronounced magnetic hysteresis at T P (susceptibility peak temperature), and its signi5cant diminishment above and below T P . The properties for some other solid solutions such as Ce 1؊x Sm x TiO 3 were also investigated. Though susceptibility peaks were found for a few of these systems, they were quite vague compared with those for the above three systems. From DC magnetization}relaxation and AC susceptibility measurements, the formation of a cluster-glass state is assumed to be a possible origin of the susceptibility peak in Ce 1؊x Nd x TiO 3 , as was suggested also for La 1؊x Sm x TiO 3 . Powder neutron di4raction measurements for Ce 0.5 Nd 0.5 TiO 3 revealed that neither long-range magnetic order nor structural changes exist below room temperature. The above interpretation supports this result. 2000 Academic Press