The present invention relates to [1] a process for producing a 2-alkyl-2-cycloalken-1-one represented by the following general formula (2), which includes the step of subjecting a 2-(1-hydroxyalkyl)cycloalkan-1-one to dehydration and isomerization in the co-existence of an acid and a platinum group metal catalyst, and [2] a process for producing an alkyl(3-oxo-alkylcycloalkyl)acetate which is useful as a perfume material, using the 2-alkyl-2-cycloalken-1-one: wherein n is an integer of 1 or 2; and R1 and R2 are each independently a hydrogen atom or an alkyl group having 1 to 8 carbon atoms with the proviso that R1 and R2 may form a ring through a carbon atom adjacent thereto.