Organosilicon guanidine derivatives RNHC(=NH)NHCH2CH2CH2Si(OC2H5)3-n (OH)n [R = H, n = 1; R = (CH2)3Si(OC2H5)3, n = 0] were synthesized by condensation of guanidinium carbonate with (3-aminopropyl)triethoxysilane. The products were brought into ether interchange with thiethanolamine and hydrolytic polycondensation.