Series of isomeric monohaloalkanoic acids may be prepared from y-or 6-alkanoic lactones by reaction with hydrogen halides. For example, y -nonanolactone in 48% hydrogen bromide under reflux affords a 1 : 1.5: 1.7:2.2:2.4 mixture of 4-, 5-, 6-, 7-, and 8-bromononanoic acids.