In the process of this invention vapours of the silicon and the aliphatic hydrocarbon or mixture thereof are preheated to a sufficiently high temperature and made to react on the hot substrate in the oxygen free reducing atmosphere such as hydrogen atmosphere. The preferred temperature range for the preheating is 800 degree - 1300 degree C and for the reaction it is 1200 degree - 1450 degree C. The flow rate of the reactant gases should be low preferably in the range of 0.1 -0.3g.cm2.h. The product obtained as a result of this reaction is fibrous silicon carbide; the diameter of the fibres is less than a micrometer and the length is in the range of 0.1 -10 mm.