The invention relates to a method for producing 3,3-dichloro-1,1,1-trifluoroacetone. This method includes a step of fluorinating pentachloroacetone by hydrogen fluoride in the presence of a fluorination catalyst. This fluorination may be conducted in a liquid phase in the presence of an antimony compound as the fluorination catalyst. Alternatively, the fluorination may be conducted in a gas phase in the presence of a fluorination catalyst which may be a fluorinated alumina or at least one compound of at least one metal selected from Al, Cr, Mn, Ni, and Co. The method is suited to an industrial scale production of 3,3-dichloro-1,1,1-trifluoroacetone. The invention further relates to another method for producing 3,3-dichloro-1,1,1-trifluoroacetone. This method includes a step of purifying a crude 3,3-dichloro-1,1,1-trifluoroacetone by a distillation in the presence of water, thereby to produce 3,3-dichloro-1,1,1-trifluoroacetone which is substantially free of organic matters other than 3,3-dichloro-1,1,1-trifluoroacetone. This crude 3,3-dichloro-1,1,1-trifluoroacetone may be the reaction products of the fluorination of pentachloroacetone in a gas phase. Due to the provision of the another method, 3,3-dichloro-1,1,1-trifluoroacetone can be produced with high yield.