Metal-free phthalocyanines are prepared by heating an o-arylene dicyanide of the benzene or naphthalene series with a small proportion of an ethanolamine. The process is rapidly effected at a comparatively low temperature and with good yields. In examples: (1) phthalonitrile is heated with a little distilled technical triethanolamine at 170--180 DEG C. for about 4 hours; the dye in crystalline form is finely subdivided by solution in concentrated sulphuric acid and precipitation by pouring into water; (2) 1.2-dicyanonaphthalene is heated in a little triethanolamine at 220--230 DEG C. for 1\ba1/2\be hours; (3) 4.5-dichlorphthalonitrile is heated with a little triethanolamine at 220--225 DEG C. for 1\ba1/2\be hours; (4) phthalonitrile is heated with a little mono- or di-ethanolamine at 170--175 DEG C. Mention is also made of 3-and 4-chlorphthalonitriles, and 3- and 4-nitrophthalonitriles as starting materials. Specifications 322,169, [Class 2 (iii)], 389,842, 390,149, and 410,814 are referred to.