NEW MATERIAL: A compound of formula I (R is 1˜6C alkyl other than ethyl, 2˜6C alkenyl).EXAMPLE: 2-Methyl 2-mercaptopropionate.USE: A durable flavor and taste imparting agent usable for foods, drinks, cosmetics, healthy and hygienic use, medicines, etc.PROCESS: A 2-mercaptopropionic acid of formula II (R′ is H, 1˜6C alkyl or 2˜6C alkenyl) is esterified with an aliphatic alcohol of the formula R′(OH) in the presence of a catalyst, e.g. an inorganic acid such as sulfuric acid or organic acid such as acetic acid, in an azeotropic solvent, e.g. benzene, at 60˜100° C. to give the compound of formula I easily in high purity and yield. The molar amount of the aliphatic alcohol to be used is 1˜20 times, preferably 2˜5 times, that of the compound of formula II. The amount of the catalyst to be used is 0.1˜10 wt % based on the compound of formula II.