The dielectric and piezoelectric properties of [1 1 1]-oriented orthorhombic Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT) single crystals (3O multi-domain state) with various domain sizes were investigated by poling control. The free dielectric permittivity (ε33T/ε0) and longitudinal piezoelectric coefficient (d33) were 6400 and 900 pC N-1, respectively, for samples with domain sizes of ∼2 μm, nearly twice that of ∼20 μm. Together with good temperature stability (Δd33/d33(25C) <8%) up to the orthorhombic-tetragonal phase transition temperature, the "3O" PMN-PT crystals with fine domain structures are promising candidate for sensors and transducers. © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.