Abstract: An .alpha.-formyl sulfide is prepared by a process which comprises reacting in an aqueous medium an .alpha.-haloaldehyde of the formula ##EQU1## wherein R' and R" independently are hydrogen, hydrocarbon radicals of 1 to 18 carbon atoms selected from the group consisting of alkyl, cycloalkyl, alkenyl, cycloalkenyl and aryl, or substituted hydrocarbon radicals of the above group, and X is a halogen selected from the group consisting of chlorine, bromine, and iodine, with a thiol salt of the formula R"'SM, wherein R"' is a hydrocarbon radical of 1 to 18 carbon atoms selected from the group consisting of alkyl, cycloalkyl, alkenyl, cycloalkenyl and aryl or a substituted hydrocarbon radical of the above group; and M is an alkali or alkaline earth metal, thereby forming an .alpha.-formyl sulfide of the formula ##EQU2## Also, 2-hydrocarbylthioaldoximes are prepared by oximating the above .alpha.-sulfides by reaction with a source of hydroxylamine.