The novel organosilicon compound of the invention is an .omega.-silylalkynyl silane compound represented by the general formula R.sub.3 SiC.tbd.C(CH.sub.2).sub.n Si(CH.sub.3).sub.m X.sub.3-m, in which each R is, independently from the others, a hydrogen atom, lower alkyl group or aryl group, X is a halogen atom or a lower alkoxy group, the subscript m is 0,1 or 2 and the subscript n is an integer in the range from 10 to 30 which forms a uniform monomolecular layer on a substrate surface with silyl ethynyl groups arranged in alignment. The compound can be prepared by a Grignard reaction starting form an .omega.-silylalkynyl halide represented by the general formula R.sub.3 SiC.tbd.C(CH.sub.2).sub.n Y, in which R and n each have the same meaning as defined above and Y is a halogen atom, and a methyl alkoxy or halosilane of the formula (CH.sub.3).sub.m SiX.sub.4-m, in which X and m each have the same meaning as defined before.