Abstract: A novel process for the manufacture of a .gamma.-halotiglic aldehyde HalH.sub.2 C-CH.dbd.C(CH.sub.3)-CHO [I], wherein Hal signifies chlorine or bromine, comprises haloalkoxylating a 1-alkoxy-2-methyl-1,3-butadiene H.sub.2 C.dbd.CH-C (CH.sub.3).dbd.CH-OR.sup.1 [II], wherein R.sup.1 signifies C.sub.1-4 -alkyl, using a particular halogenating agent in a C.sub.1-4 -alkanol (R.sup.2 OH) and hydrolyzing the thus-obtained .gamma.-halotiglic aldehyde dialkyl acetal HalH.sub.2 C-CH.dbd.C(CH.sub.3)-CH (OR.sup.1)(OR.sup.2) [III] to the desired .gamma.-chloro- or .gamma.-bromotiglic aldehyde I. The halogenating agent used in this process is selected from an alkali metal hypochlorite, an alkali metal hypobromite, an alkaline earth metal hypochlorite, an alkaline earth metal hypobromite, tert.butyl hypochlorite, N-bromoacetamide, 1.3-dichloro-5,5-dimethylhydantoin and 1,3-dibromo-5,5-dimethylhydantoin. Further aspects of the present invention are the use of the thus manufactured .gamma.