A process for preparing oxadiazole compounds of formula I, wherein A is phenyl or a 5- or 6-membered aromatic heterocycle; wherein the ring member atoms of the aromatic heterocycle include besides carbon atoms 1, 2, 3, or 4 heteroatoms selected from N, O, and S as ring member atoms with the provision that the heterocycle cannot contain 2 contiguous atoms selected from O and S; and wherein A is further unsubstituted or further substituted with additional n identical or different radicals R A; wherein n is 0,1, 2, 3, or 4; R A is independently selected from the group consisting of halogen, cyano, C 1 -C 6 -alkyl, C 1 -C 6 -haloalkyl, C 1 -C 6 -alkoxy, and C 1 -C 6 -haloalkoxy; R is methyl, which is further unsubstituted or further substituted with additional 1, 2, or 3 identical or different radicals R X; wherein R X is hydrogen, halogen, oxo, or OH; the process comprising reacting an amidoxime compound of formula II, wherein the variables A and R are as defined above for compounds of formula I, with a haloacetic ester of formula II.a, wherein R 5 is C 1 -C 6 -alkyl; in the presence of a base selected from the group consisting of alkali metal C 1 -C 6 -alkoxides, alkali and earth alkali metal carbonates, alkali and earth alkali metal hydroxides, tri-(C 1 -C 6)-alkylamines, pyridine, N -methylimidazole or quinoline, pyridine, collidine, lutidine, 2-picoline, 3-picoline, 4-picoline, N,N- dimethyl-4-aminopyridine, 5-ethyl-2-methyl-pyridine, DBU, and TBD; and at a temperature between 20°C and 45°C; characterized in that the process is conducted in the absence of an auxiliary solvent. A is phenyl or a 5- or 6-membered aromatic heterocycle; wherein the ring member atoms of the aromatic heterocycle include besides carbon atoms 1, 2, 3, or 4 heteroatoms selected from N, O, and S as ring member atoms with the provision that the heterocycle cannot contain 2 contiguous atoms selected from O and S; and wherein A is further unsubstituted or further substituted with additional n identical or different radicals R A; wherein n is 0,1, 2, 3, or 4; R A is independently selected from the group consisting of halogen, cyano, C 1 -C 6 -alkyl, C 1 -C 6 -haloalkyl, C 1 -C 6 -alkoxy, and C 1 -C 6 -haloalkoxy; n is 0,1, 2, 3, or 4; R A is independently selected from the group consisting of halogen, cyano, C 1 -C 6 -alkyl, C 1 -C 6 -haloalkyl, C 1 -C 6 -alkoxy, and C 1 -C 6 -haloalkoxy; R is methyl, which is further unsubstituted or further substituted with additional 1, 2, or 3 identical or different radicals R X; wherein R X is hydrogen, halogen, oxo, or OH; the process comprising reacting an amidoxime compound of formula II, wherein the variables A and R are as defined above for compounds of formula I, with a haloacetic ester of formula II.a, wherein R 5 is C 1 -C 6 -alkyl; in the presence of a base selected from the group consisting of alkali metal C 1 -C 6 -alkoxides, alkali and earth alkali metal carbonates, alkali and earth alkali metal hydroxides, tri-(C 1 -C 6)-alkylamines, pyridine, N -methylimidazole or quinoline, pyridine, collidine, lutidine, 2-picoline, 3-picoline, 4-picoline, N,N- dimethyl-4-aminopyridine, 5-ethyl-2-methyl-pyridine, DBU, and TBD; and at a temperature between 20°C and 45°C; characterized in that the process is conducted in the absence of an auxiliary solvent.