T-2(n, pi*) phosphorescence has been observed for 4-hyroxybenzaldehyde along with T-1(p, pi*) phosphorescence in a partially translucent 1,4-dichlorobenzene host upon increasing temperature. Quantitative analysis of the steady-state emission spectra and emission decay profiles measured as a function of temperature provides estimates for the excited-state energies and rate constants that characterize the excited-state dynamical behavior of 4-hydroxybenzaldehyde. It is shown that the successive occurrence of the T-1(pi, pi*) and T-2(n, pi*) phosphorescence is caused by the thermal repopulation from the T-1 state. (C) 2013 Elsevier B.V. All rights reserved.