The acetates of neopentyl-type polyols, (R)n-C-(CH2OCOCH3)4-n(n=0, 1, 2), such as pentaerythritol tetraacetate, pentaglycerine triacetate, and neopentylglycol diacetate, undergo stepwise chlorination upon treatment with gaseous hydrogen chloride in the presence of zinc chloride. The fully chlorinated products, (R)n-C- (CH2Cl)4-n, however, can be obtained with difficulty. In order to clarify the mode of reactions, the acetates (0.334 mol) of various neopentyl-type polyols and some straight chain primary alcohols were treated at 160°C in the presence of zinc chloride catalyst (0.0081 mol) under the constant flow of gaseous hydrogen chloride, 500 ml/min, and the chlorination velocities measured. The results indicate that the ?A-substituent is the factor which affects the rate of reaction. When all the hydrogen atoms on the β-carbon of primary alcohol moieties are replaced by any substituent other than acetoxymethyl group, the chlorination velocity constant was ca . 10-5min-1. This value is far small when compared with that for the acetate of the unsubstituted alcohol (ca . 10-2min-1). However, when the substituents include at least one acetoxymethyl group, the value becomes to be in the order of 10-2min-1 .