To obtain a functional powder highly dispersible in a vehicle or a resin by mixing fine particles of a metal compound with a fluorocompound and firing the mixture to grow the particles and also to inhibit the aggregation and sintering of the particles by the firing.

In growing fine particles of a metal compound by heating and firing the particles, 0.1 to 5.0% by weight (in terms of fluorine) of a fluorocompound is mixed in fine particles of a metal compd. such as a metal oxide, e.g. a titanium oxide, a tin oxide or a zinc oxide, or a metal hydroxide, e.g. an iron hydroxide having an average particle diameter of below 0.1μm, and the resultant mixture is fired at a temperature of 500°C or above to obtain particles having an average diameter of 0.1 to 20μm while inhibiting the aggregation.