Which of the two, Hydroxide anion OH- and Methoxide ion OCH3-, is a better nucleophile in aqueous medium?? I have 2 arguments both against each other. First, Oxygen atom in methoxide has higher negative charge density due +I effect of C atom, so methoxide should be the better nucleophile. Second, as methanol is a stronger acid than water, so OH- should be a stronger base, and hence OH- should be a better nucleophile. I was also thinking of solvation effect, like it happens in halogen family, which complicates the matter.