The effect of CaC2 on the activity of MFI-supported molybdenum catalysts was investigated in the dehydrocyclization of methane. Treatment with CaC2 enhanced the activities of the catalysts in comparison to the activities of those which were not precarburized or prepared by precarburization with a CH4/H-2 mixture. The induction period seen in the case of the sample prepared without precarburization decreased with CaC2 treatment. CaC2 loading above a certain value, however, gave poor results, possibly One to pore blockage in the support. All samples, precarburized with CaC2 or CH4/H-2 mixture or carburized in the course of the reaction, deactivated in a similar manner after the variable induction period. (C) 2004 Elsevier Inc. All rights reserved.