be used to initiate the metathesis step characterising the method of the invention tetrathionates such as na 2 s 4 o 6 2h 2 o and other similar thionate species such as dithionates trithionates pentathionates and heptathionates are all fit for this purpose and also gaseous so 2 possesses both the reducing power and the sulphur availability to produce amorphous m x s y moieties on a selected support the support carbon particles have preferably a surface area comprised between 200 and 300 m 2 g and the preferred specific loading of the resulting rhodium sulphide on carbon is comprised between 12 and 18 the sequence of addition of the reactants is critical to obtain the desired product to the solution containing the suspended carbon particles and the rhodium precursor salt the selected sulphur source for instance a tiosulphate or thionate species is added so that the metathesis process can initiate simultaneously or immediately after depending on the specific reaction a strong reducing agent defined as a species with a reduction potential below 0 14 v she is added in small aliquots as reducing agent sodium borohydride nabh 4 is preferred but other suitable reactants include lialh 4 hydrazines formaldehyde and metallic aluminium zinc or antimony the reducing agent as defined has a reduction potential below the one of s 0 s u2212 2 couple in this way it can achieve the instantaneous metathesis of the metal ions and of the thiosulphate part directly forming amorphous rhodium sulphide on the carbon support particles while preventing the formation of discrete reduction states which are the main factor controlling the yield and phase distribution of the different sulphide moieties the method of the invention can be applied to the manufacturing of other single crystalline phases of.