PURPOSE: To obtain the titled compound in high yield with reducing costs required for reaction devices and reaction processes under mild reaction conditions in a short time, by using a heteropoly-acid containing W or Mo as a dehydrating catalyst, dehydrating a specific alcohol.

CONSTITUTION: An alcohol compound such as 1-(o-trifluoro-methylphenyl)ethanol, etc. shown by the formula I (R is H, or CH3) in the presence of a heteropoly- acid containing W or Mo shown by the formula II(n is 3 or 4; X is one or more atoms selected from P, As, Si, Ge and Ti) as a dehydrating catalyst at ≥100°C, preferably at 100W170°C for 0.2W2hr at 50W760Torr, to give the desired compound such as o-trifluoromethylstyrene, etc. shown by the formula III. 12-Tungstophosphoric acid, 12-tungstosilicic acid, 12-molybdophosphoric acid, 12-molybdosilicic acid, etc. may be used as the dehydrating catalyst.