The invention relates to a process for the preparation of spiro [(4-cyclohexanone)-[3H]indol]-2′[1′H]-one derivatives of general formula I—wherein R1 and R2 independently stand for hydrogen, C1-4alkyl, C1-4alkoxy, C1-4alkylthio, C1-4polyfluoroalkyl, C1-4polyfluoroalkoxy, C3-7cycloalkyloxy, C3-7cycloalkylthio, phenoxy, benzyloxy or nitro group—, characterized by reacting an indolin-2-one derivative of general formula II—wherein R1 and R2 are as defined above—with a compound capable for introducing a protective group, coupling the compound of general formula III, thus obtained—wherein R1 and R2 are as defined above and A stands for a protective group—with acrylic acid C1-4ester; cyclizing the resulting compound of general formula IV—wherein R1 and R2 are as defined above—with a compound capable for introducing a protective group, coupling the compound of formula III thus obtained,—wherein R1 and R2 are as defined above and A stands for a protective group—with an acrylic acid C1-4ester, cyclizing the resulting compound of formula IV—wherein R1 and R2 are as defined above R3 stands for C1-4alkyl and A stands for a protective group—, eliminating the—COOR3 group and the A protective group of the keto-ester of general formula V—wherein R1 and R2 are as defined above, R3 stands for C1-4alkyl and A stands for a protective group—, optionally without isolation of the compounds of general formulae IV and/or V and/or VI.