The deep red luminescence of Mn4+ in the distorted perovskite Gd2MgTiO6 is reported and discussed. The excitation spectrum of Mn4+ luminescence is dominated by the O2- to Mn4+ charge-transfer transition at similar to 31,700 cm(-1). The luminescence is due to the (2)E --> (4)A(2) transition with the zero-phonon line at similar to 14,685 cm(-1) and the associated side bands at longer wavelengths. Evidence is presented for the occurrence of multiple Mn4+ sites in the host lattice. This is attributed to the deviation from a perfect 1:1 order between the B-site ions (Mg2+/Ti4+) of the perovskite lattice. The unactivated host lattice also exhibits Mn4+ luminescence due to the presence of this ion as an impurity in one of the starting materials (TiO2). Evidence is presented for Gd3+ to Mn4+ energy trans this host lattice.