PURPOSE: To readily produce an isocyanate compound useful as a raw material or an intermediate, etc., for producing medicines, agricultural chemicals, dyes, etc., by reacting a haloalkanoyl isocyanate with a dehydrohalogenating agent.

CONSTITUTION: A compound expressed by formula III (R is H or lower alkyl) is reacted with a compound expressed by the formula (COX)2 (X is halogen) to provide a haloalkanoyl isocyanate expressed by formula II, which is then used as a starting raw material and reacted with a dehydrohalogenating agent (e.g. molecular sieve) to afford an alkenoyl isocyanate (e.g. acryloyl isocyanate expressed by formula I. The compound expressed by formula I is a stable liquid at ordinary temperature, readily handleable and soluble in various organic solvents, it is readily usable as a solution. If the aforementioned alkenoyl isocyanate is allowed to stand under natural conditions, it reacts with moisture to readily afford amides. Thereby, it has advantages in low environmental pollution or residual properties. Furthermore, the above-mentioned compound is also useful as a synthetic raw material for heat-resistant resins, surfactants, hydrophilic resins, etc.