CaSnO3:Eu3+ microcrystals with controlled morphology were prepared by a hydrothermal method followed by further calcining treatment Without any template or capping reagents. Reactant concentration and reaction time showed strong effects on the phase formation and morphology of the products. The prepared samples were systematically characterized by powder X-ray diffraction, field-emission scanning electron microscopy, photoluminescence (PL), and photoluminescent excitation spectra. The possible formation mechanism was proposed. Furthermore, PL characterization of CaSnO3:Eu3+ microcrystals was performed and discussed in detail. (C) 2009 The Electrochemical Society. [DOI: 10.1149/1.3190536] All rights reserved.