The structure of the title compound, N-(5-hydroxysalicylidene)-2,4,6-trimethylaniline, C 16 H 17 NO 2 , has been resolved in order to study the influence of intermolecular hydrogen-bond networks on the thermochromic and photochromic properties of salicylideneaniline. The molecules stack in layers and are associated by an infinite chain of hydrogen bonds. The mean distance between the planes of the two layers is about 3.37 A. The two C-O [1.365(4) A] and the C7-N [1.273(4)A] distances show that the phenol-phenol form is the major conformation. The title compound is thermochromic.