PURPOSE: To produce naphthoquinone useful as a raw material of dyes and organic syntheses, in high yield and efficiency, at a low reaction temperature, with reduced load of the step to separate the unreacted naphthalene, by carrying out the vapor-phase oxidation of naphthalene using a specific catalyst having high activity.

CONSTITUTION: Naphthoquinone is produced by the vapor-phase reaction of naphthalene at a space velocity of 1,000W6,000hr-1 and 250W500°C in the presence of an oxide catalyst prepared by supporting a catalyst composition of formula I (V is vanadium; K is potassium; S is sulfur; Fe is iron; Sn is tin; X is a carrier element such as silicon, titanium, aluminum, etc.; aWg are atomic ratios of the elements; a:b:c:d:e:f=10:(10W100):(5W100):(0.1W10):(0.05W10):(10W300); g is dependent number determined by the values of aWf and the state of the oxide), e.g. the composition of formula II, formula III, formula IV, etc., on an inert bulk carrier.

EFFECT: The problem of temperature control can be solved, and the objective compound can be produced industrially in a mass.