The present invention relates to a process for preparing 3-difluoromethyl-substituted pyrazole compounds of the formula (I) in which R1 is H, halogen, nitro, C1-C8-alkyl, C1-C8-haloalkyl, C3-C8-cycloalkyl, phenyl, naphthyl, hetaryl, cyano, —C(═O)—OR1a, —C(═O)—NR1bR1c, —C(═O)—SR1d or —C(═S)—SR1e; R2 is H, C1-C4-alkyl, benzyl or phenyl; R3 is H, halogen, C1-C8-alkoxy, C1-C8-haloalkoxy, C3-C8-cycloalkoxy, C2-C8-alkenyloxy, C1-C8-alkylthio, C1-C8-haloalkylthio, C3-C8-cyclo-alkylthio or C2-C8-alkenylthio; compounds of the formula (II.a) or (II.b), in which R1 and R3 each have one of the definitions given above; R4 is halogen, —OR4a, —SR4a, —O—SO2—R4a or an —NR4bR4c group; R5 and R6 are each C1-C8-alkyl, C1-C8-haloalkyl, C3-C8-cycloalkyl, benzyl or phenyl, or, together with the nitrogen atom to which they are bonded, are a 3- to 8-membered heterocycle; Lewis acid adducts of compounds of the formula (II.b); the use of compounds of the formula (II.a) or (II.b) and of the Lewis acid adducts for preparing compounds of the formula (I) or (VI); and to a process for converting such compounds to the corresponding 3-difluoro-pyrazol-4-ylcarboxylic acids.