A process can prepare a colourless, methanolic solution of 3-(N-benzyl-2-aminoethyl)aminopropyltrimethoxysilane hydrochloride. The process includes, in step 1 fractionally distilling the vinylbenzyl chloride reactant component with addition of at least one stabilizer, and in step 2, metering and mixing the distillate (vinylbenzyl chloride) from step 1 into an initial charge of N-(2-aminoethyl)-3-aminopropyltrimethoxysilane and methanol in a molar ratio of the N-(2-aminoethyl)-3-aminopropyltrimethoxysilane to vinylbenzyl chloride of 1.0:0.80 to 1.0:1.15 and at a temperature in the range from 40 to 60° C. and leaving them to react further. The colourless, methanolic solution has an APHA colour number of