Ab initio calculations for the O-CH3 insertion/HI elimination reactions of CH2I-I with methanol (CH3OH) were done to examine the chemical reactivity of CH2I-I with methanol molecules. It was found that CH2I-I reacts with methanol to form an iodoether (CH2I-OCH3) product and a HI leaving group similar to the O-H insertion/HI elimination reactions of CH2I-I with water. The barrier to reaction decreases as the number of methanol molecules increase suggesting that methanol can catalyze this reaction. A brief comparison of the O-Y (Y = CH3, H) insertion/HI elimination reactions of CH2I-I with methanol to the corresponding reactions with water was done. We found that methanol is less effective in catalysis of the insertion/elimination reactions, which may due to less hydrogen bonding in the methanol solvated clusters compared to water solvated clusters. (C) 2004 Elsevier B.V. All rights reserved.