The present invention relates to a method of forming metal-containing nanoparticles or oxides thereof, in particular metal alloy nanoparticles. The method comprises the steps of providing at least two different transition metal ions by providing at least two metal ion-containing compounds; A heating step in which two or more metal ion-containing compounds are exposed to a temperature of 300° C. or higher to form metal alloy nanoparticles; A cooling step comprising cooling the product of step b; Each metal ion-containing compound is a transition metal complex having a ligand coordinated to the transition metal ion, the ligand being glyoxime; Glyoxime derivatives; Salicylaldimine; And salicylaldimine derivatives. The preferred method is a solution based method. The products of this method are also described, and their use as electrocatalysts as well as the use of metal ion-containing compounds for producing nanoparticles.