Coating films of CH3SiO3/2 on sapphire, SiO2 glass, and metallic substrates have been prepared from an aluminium acetylacetonate catalyzed oligomer solution. The coating films are treated in atmospheres of gaseous amines. The reaction is monitored by using an infrared absorption of Si-OH at 3000-3700 cm(-1). The polymerization of silanols in the coating films proceeds at an elevated treatment temperature. The degree of polymerization becomes larger with the exposure to amines. indicative of a catalytic effect of gaseous amines on the polymerization.