Abstract: Fluorine-containing carbonyl compounds of the formula ##STR1## and its optically active isomers, which are useful for liquid crystal, bioactive substances, medicines, agricultural medicines such as fungicides, herbicides and hormones, organic functional materials and LB membranes, prepared by the reaction with trifluoro acetoaldehyde and RCOCH.sub.3, wherein R is a substituted or not-substituted lower alkyl group, preferably a lower alkyl having not more than 10 carbon atoms, a substituted or not-substituted aromatic group or a substituted or not-substituted arylalkyl group.