Abstract The preparation of monohalomethyllithium XCH 2 Li is achieved by Bromine-lithium exchange from the corresponding Bromohalomethane in the presence of one equivalent of lithium bromide at− 110 in THF-Ether-Pentane solutions. This reagent, on coupling with various carbonyl compounds leads to halohydrins, epoxides and α-halomethyl ketones with high yields.