Several v = 0-4 series of hot bands in the 36 000-39 000 cm(-1) spectral region have been recorded from the MgO(a (3)Pi(2)) metastable state (produced by the products of laser vaporization of a magnesium rod reacting with N2O) to higher-lying MgO((3)Pi(2)) vibronic levels, and have been rotationally resolved. From the analysis of the spectra, rotational and vibrational spectroscopic constants for this interesting low-lying MgO(a (3)Pi(2)) excited state, which formally has Mg+O-'open-shell' character, have been determined. (C) 2003 Elsevier B.V. All rights reserved.