To obtain mixtures of isomeric substituted phthalocyanines, particularly useful as optical information materials of a WORM type by the reaction of phthalodinitrile compounds in the presence of a metal salt and a Lewis acid.

Desired mixtures comprise isomeric α-alkoxy-substituted phthalocyanines of formula II (wherein Me is a divalent metal atom or a divalent oxo metal) or the like or isomeric β-alkoxy-substituted phthalocyanines of formula III or the like which can be obtained by reacting a compound of formula I (wherein R1 is substitutable 1-16C alkyl, 3-16C alkenyl or 3-16C alkynyl) with an equimolar amount of urea in the presence of a metal salt such as Pd(II)Cl2 and a Lewis acid such as ammonium molybdate at 130-250°C (preferably 130-190°C) at a pressure of 1×105-20×105 Pa in a solvent such as nitrobenzene. The mixture have high NIR absorption in the range of 700-900 nm.