For protecting tin from tarnishing, laurylamine has been found to be more effective than other antitarnish agents. A 10 min treatment in 2.5 g dm(-3) of laurylamine solution at pH 8 and 70 degrees C forms a coating on tinplate with better protective ability and good solderability. The results of X-ray photoelectron spectroscopy and Auger electron spectroscopy analyses show that the coating formed has the average composition of 39.0% O, 48.7% Sn, 7.9% N and 4.4% C. From differences in the binding energies of Sn and N before and after film formation, it is deduced that N in laurylamine is coordinated with Sn in the film.