The methanol conversion and a feasible methanol co-reaction with methyl iodide were studied on a vanadium incorporated MCM-41 type (V-MCM-41) mesoporous catalyst. which was prepared by a direct hydrothermal synthesis method. Adsorption/desorption as well as conversion derivates of radioactive methanol were easily followed by radioactivity detectors on V-MCM-41. The transformation and coreaction products were analyzed by a gas chromatograph equipped with Radio/FID detectors. The radiodetector was applied to distinguish C-11-derivates from the non-radioactive methyl iodide and its derivates. The radio-labeling method proved methanol transformation to methylal and, in the presence of methyl iodide, decided the roles of methyl group and iodide of methyl iodide in newly synthesized methyl iodide formation in the absence of oxygen gas. (C) 2008 Elsevier B.V. All rights reserved.