PURPOSE: To economically produce the fine alloy powder capable of being stably treated at high temp. by heat-treating the composite fine powder of silver and platinum or palladium in a molten alkali salt and alloying the composite fine powder.

CONSTITUTION: An aq. soln. of an ammoniacal silver nitrate complex is added to a colloidal soln. of platinum or palladium to reduce the complex, and the composite fine powder of silver and platinum or silver and palladium is obtained. The composite fine powder is added to an alkali salt, and a small amt. of water is further added and sufficiently mixed. NaOH, KOH, Na2CO3, K2CO3, Na2SO4, etc., are appropriately used as the alkali salt. The mixture is then heated while preventing bumping and heat-treated at about 300-600°C to alloy the composite fine powder. The alkali salt is dissolved in water and removed. Consequently, a stable fine alloy powder without causing oxidation, expansion, shrinkage, dissolution and separation of the component metals in the high temp. heat treatment, etc., is obtained.