Salt of thioctic acid with L-carnitine with the formula: AY(X).sub.x where A is ##STR00001## where Y is the cation of an alkaline metal, of an alkaline earth metal or is a quaternary ammonium group, X is A or OH.sup.-, x is equal to 0 when Y is the cation of an alkaline metal or a quaternary ammonium group and equal to 1 when Y is an alkaline earth metal.