There is disclosed a new product of the benzanthrone class, namely, 1-aza-2-hydroxy-benzanthrone, useful in the synthesis of vat and azoic dyes. Briefly, the new product is obtained by reacting 1,4-napthoquinone with methyl-3,5-hexadienoate, under heating, and then treating the resulting solid product with excess NH3 in anhydrous alcoholic solution, and finally recovering the 1-aza-2-hydroxy benzanthrone.