This work examined the transport parameters in Alq thin films and their effects on the luminescence efficiency. Data were obtained from Chen et al. (Appl Phys Lett 75 (1999) 4010) and a comprehensive treatment was given to the determination of the transport parameters. It has been observed that a higher (effective) electron density is not essential for better device performance while there appeared to be a closer correlation between higher mobility and better luminescence efficiency. The increase in carrier mobility with improved film quality was hampered at high field (> 1.2 MV/cm). The authors have attempted to correlate the field dependent mobility with a barrier height lowering space charge effect and our results suggested a barrier height of 0.615 eV indicating possible trap states near the Fermi level within the Alq layer. (C) 2002 Elsevier Science Ltd. All rights reserved.