We report the first measurements of delayed ionization of the metallofullerene La@C-82. When highly excited in laser desorption, La@C-82 was found to ionize over several microseconds. The rate of delayed ionization of La@C-82 was compared to C-60 under the same extraction conditions, and found to be significantly different. A theoretical model was used for the fitting of the ion signal of the two fullerenes. The metallofullerene results can be fitted well over a time window <30 mus and are consistent with a low ionization potential (6.3 eV) and a high radiative cooling rate. The C-60 data cannot be fitted over the same time window, indicative of an additional time-dependent competing decay channel.