The invention relates to a process for preparing semicarbazone compounds of the formula I, where R1 and R2 are each independently hydrogen, halogen, CN, C1-C4-alkyl, C1-C4-alkoxy, C1-C4-haloalkyl or C1-C4-haloalkoxy, and R3 is C1-C4-alkoxy, C1-C4-haloalkyl or C1-C4-haloalkoxy, by reacting a hydrazone compound of the general formula II, where R is C1-C4-alkoxy, amino, C1-C4-alkylamino or di(C1-C4-alkyl)amino, and R1, R2 are each as defined above, with an aniline compound of the general formula III where R3 is as defined above.