Highly pure amidosilanes of the formula ##STR1## wherein R is alkyl having 1 to 18 carbon atoms, cycloalkyl having 5 to 18 carbon atoms, alkenyl having 2 to 18 carbon atoms and aryl having 6 to 18 carbon atoms,R.sup.1 is alkoxy having 1 to 18 carbon atoms,R.sup.2 and R.sup.3 each independently of one another are alkyl having 1 to 18 carbon atoms or aryl having 6 to 18 carbon atoms,x is 1, 2 or 3,y is 0, 1 or 2, with the sum of x and y being 1 to 3,are produced by reacting an alcohol-free suspension of alkali metal salts or organic amides with organosilanes wherein said salts of amides are prepared by reacting a compound of the formula ##STR2## with an alcoholic solution of an alkali metal alcoholate in inert organic solvents and the removing alcohol from the reaction mixture by distillation, and said organosilanes are of the formulaR.sub.x R.sub.y.sup.1 SiX.sub.4-(x+y)wherein X is a halogen or a carboxylate moiety having 1 to 18 carbon atoms, with the reaction being carried out with the exclusion of moisture in inert organic solvents.