Abstract: A siloxane treating composition comprises (1) a mixture and/or a reaction product of (A) a polydiorganosiloxane having at least one silicon-bonded --OX group, X being H, alkyl or alkoxyalkyl and at least one silicon-bonded aminoalkyl or polyaminoalkyl acid salt group, and (B) a silicon compound having more than 2 silicon-bonded groups which are reactive with --OX of (A), and (2) a water-soluble solvent for (A) which comprises one or both glycol ethers of the formula C.sub.4 H.sub.9 --O--(CH.sub.2 --CH.sub.2 --O).sub.n H where n is 1 or 2. These compositions have improved penetration ability and stability, especially when used as aqueous composition for rendering substrates, such as masonry, hydrophobic.Also claimed is a process for making such compositions and a process for applying them to substrates.