The up‐converted hot luminescence technique was utilized to obtain information on the nonradiative relaxation in Ni2+:MgO. The experiment shows the presence of an electronic bottleneck associated with the3T1(t4e4) electronic state which was determined to be at 2.973±0.003 eV (23978±25 cm−1). The spectral profiles indicate that the 395±15 cm−1phonon mode is involved in the nonradiative relaxation of the impurity Ni2+ions. ©1995 American Institute of Physics.