Spherical polysilsesquioxane particles are prepared by reacting trialkoxysilanes of formula, (I)RSi(OR1)3 ； ；(I),whereR represents a C1-16 hydrocarbon radical whose carbon chain may be interrupted by nonadjacent —；O—； groups,R1 represents a C1-4 alkyl radical,with acidified water having a pH≤；6 with stirring to produce a hydrolysate, in a second step mixing the hydrolysate with a solution of NaOH and/or KOH,and in a third step storing the mixture is stored for at least 8 h before isolating polysilsesquioxane particles thus formed.
