This invention relates to anti-cancer compounds and to methods for treating orpreventing cancer. In one aspect theinvention concerns mitochondrially delivered pro-oxidant anti-cancer compoundsthat generate reactive oxygen species and induceapoptosis of cancerous cells. The delivery moiety can be a lipophilic cationand the pro-oxidant moiety can be a pro-oxidantvitamin E analogue, such as .alpha.-tocopheryl succinate, .alpha.-tocopherylmaleate, .alpha.-tocopheryl maleyl amide, or 2,5,7,8-tetramethyl-2R-(4R,8R,12-trimethyltridecyl)-chroman-6-yloxyacetic acid (.alpha.-tocopheryloxyacetic acid).