A process for preparing a siloxane compound comprising a 2-hydroxyphenyl benzotriazole function which comprises at least one step in which a reaction for hydrosilylation of a compound 2-hydroxyphenyl benzotriazole comprising a substituent having a terminal double bond with a siloxane compound comprising an SiH function is carried out in the presence of a catalyst and of at least one volatile organic solvent corresponding to one of formula (VII) or (VIII). in which R4 and R5, which may be identical or different, represent a linear or branched C1-C4 alkyl radical, with the proviso that the sum of the carbons of R4 and R5 is less than or equal to 6;y is and integer between 1 and 3;R6 which may be identical or different, are linear or branched C1-C3 alkyl radicals, with the proviso that the sum of the carbons of R6 is less than or equal to 6 is disclosed.