We present an investigation of dynamical processes of nonradiative energy transfer (ET) in Y3Al5O12: Ce3+, Pr3+, Cr3+ phosphor. The analysis based on Inokuti-Hirayama model indicates that the ET from the lowest 5d state of Ce3+ to the T-4(2g) state of Cr3+, and from the state D-1(2) of Pr3+ to T-4(2g) state of Cr3+ are both governed by electric dipole-dipole interaction. For Pr3+ concentration of 0.005 in YAG: Pr3+ Cr3+ and for Ce3+ concentration of 0.01 in YAG: Ce3+ Cr3+ the rate constant and critical distance are evaluated to be 7.3x10(-37) cm(6)s(-1) and 0.22 nm for Pr3+ - Cr3+ ET and 1.03x10(-36) cm(6)s(-1) and 0.63 nm for Ce3+ - Cr3+ ET, respectively. (C) 2012 The Electrochemical Society. [DOI: 10.1149/2.054204jes] All rights reserved.