The present invention relates to compounds of formula I, in which at least one of R5, R6 and R7 is SR12, S(O)R12 or S(O)2R12 group where R12 is a C1-6haloalkyl group, that act, as chemical uncouplers. Compounds of the invention are useful in the treatment, including prevention, of obesity, diabetes and a number of diseases or conditions associated therewith. ##STR00001##