We have measured the drift mobility of electrons and holes in thin, vapor-deposited films of tris(8-hydroxyquinolinolato-N1,O8) aluminum using a time of flight photoconductivity technique. The drift of mobility of both carriers is dispersive and strongly electric field and temperature dependent. At ambient temperature and an electric field of 4×105 V cm−1, the effective mobility of electrons and holes is 1.4×10−6 and 2×10−8 cm2 V−1 s−1, respectively, in a 400 nm thick sample.