Process for the preparation of 5-fluoro-1-alkyl-3-fluoroalkyl-1H-pyrazole-4-carbonyl halides of the formula in which R 1 is C 1 -C 6 -alkyl, R 2 is C 1 -C 5 -fluoroalkyl and X is fluorine or chlorine, comprising the stages chlorination of alkyl 1-alkyl-3-fluoroalkyl-1H-pyrazole-4-carboxylates of the formula in which R 1 and R 2 have the meanings given above and R 3 is a linear or branched C 1-12 -alkyl group, in the presence of a chlorinating agent to give alkyl 5-chloro-1-alkyl-3-fluoroalkyl-1H-pyrazole-4-carboxylates of the formula, in which R 1, R 2 and R 3 have the meanings given above; (2a-i) fluorination of the alkyl 5-chloro-1-alkyl-3-fluoroalkyl-1H-pyrazole-4-carboxylates of the formula in the presence of a fluorinating agent of the formula, in which M + is Li +, Na +, K +, Cs + or Alk 4 N + and Alk is C 1 -C 4 -alkyl, to give alkyl 5-fluoro-1-alkyl-3-fluoroalkyl-1H-pyrazole-4-carboxylates of the formula and (2a-ii) hydrolysis of the alkyl 5-fluoro-1-alkyl-3-fluoroalkyl-1H-pyrazole-4-carboxylates of the formula to give 5-fluoro-1-alkyl-3-fluoroalkyl-1H-pyrazole-4-carboxylic acids of the formula (VIa) and (2a-iii) subsequent halogenation to give 5-fluoro-1-alkyl-3-fluoroalkyl-1H-pyrazole-4-carbonyl halides of the formula, in which X is fluorine or chlorine; or (2b-i) hydrolysis of the alkyl 5-chloro-1-alkyl-3-fluoroalkyl-1H-pyrazole-4-carboxylates of the formula to give 5-chloro-1-alkyl-3-fluoroalkyl-1H-pyrazole-4-carboxylic acids of the formula, (2b-ii) subsequent halogenation of the 5-chloro-1-alkyl-3-fluoroalkyl-1H-pyrazole-4-carboxylic acids of the formula (VIb) to give 5-chloro-1-alkyl-3-fluoroalkyl-1H-pyrazole-4-carbonyl halides of the formula and (2b-iii) fluorination of the 5-chloro-1-alkyl-3-fluoroalkyl-1H-pyrazole-4-carbonyl halides of the formula in the presence of a fluorinating agent of the formula, in which M + is Li +, Na +, K +, Cs + or Alk 4 N + and Alk is C 1 -C 4 -alkyl, to give the 5-fluoro-1-alkyl-3-fluoroalkyl-1H-pyrazole-4-carbonyl fluorides of the formula, in which X is fluorine. chlorination of alkyl 1-alkyl-3-fluoroalkyl-1H-pyrazole-4-carboxylates of the formula in which R 1 and R 2 have the meanings given above and R 3 is a linear or branched C 1-12 -alkyl group, in the presence of a chlorinating agent to give alkyl 5-chloro-1-alkyl-3-fluoroalkyl-1H-pyrazole-4-carboxylates of the formula, in which R 1, R 2 and R 3 have the meanings given above; (2a-i) fluorination of the alkyl 5-chloro-1-alkyl-3-fluoroalkyl-1H-pyrazole-4-carboxylates of the formula in the presence of a fluorinating agent of the formula, in which M + is Li +, Na +, K +, Cs + or Alk 4 N + and Alk is C 1 -C 4 -alkyl, to give alkyl 5-fluoro-1-alkyl-3-fluoroalkyl-1H-pyrazole-4-carboxylates of the formula and (2a-ii) hydrolysis of the alkyl 5-fluoro-1-alkyl-3-fluoroalkyl-1H-pyrazole-4-carboxylates of the formula to give 5-fluoro-1-alkyl-3-fluoroalkyl-1H-pyrazole-4-carboxylic acids of the formula (VIa) and (2a-iii) subsequent halogenation to give 5-fluoro-1-alkyl-3-fluoroalkyl-1H-pyrazole-4-carbonyl halides of the formula, in which X is fluorine or chlorine; or (2b-i) hydrolysis of the alkyl 5-chloro-1-alkyl-3-fluoroalkyl-1H-pyrazole-4-carboxylates of the formula to give 5-chloro-1-alkyl-3-fluoroalkyl-1H-pyrazole-4-carboxylic acids of the formula, (2b-ii) subsequent halogenation of the 5-chloro-1-alkyl-3-fluoroalkyl-1H-pyrazole-4-carboxylic acids of the formula (VIb) to give 5-chloro-1-alkyl-3-fluoroalkyl-1H-pyrazole-4-carbonyl halides of the formula and (2b-iii) fluorination of the 5-chloro-1-alkyl-3-fluoroalkyl-1H-pyrazole-4-carbonyl halides of the formula in the presence of a fluorinating agent of the formula, in which M + is Li +, Na +, K +, Cs + or Alk 4 N + and Alk is C 1 -C 4 -alkyl, to give the 5-fluoro-1-alkyl-3-fluoroalkyl-1H-pyrazole-4-carbonyl fluorides of the formula, in which X is fluorine.