Magnesium porphyrazinate substituted with eight (1-naphthyl) groups on the peripheral positions has been synthesized by cyclotetramerization of 3,4-(1-naphthyl)pyrroline-2,5-diimine, 4-(I-naphthyl)pyrroline-2,5-diimine in the presence of magnesium butanolate. Its demetalation by treatment with trifluoroacetic acid, resulted in a partially oxidized product, namely, octakis(1-naphthyl)-2-seco-porphyrazine-2,3-dione. Further reaction of this product with copper(II) acetate, zinc(II) acetate and cobalt(II) acetate led to the metallo derivatives, [octakis(I-naphthyl)-2-seco-2,3-dioxoporphyrazinato]M(II) (M = Cu, Zn or Co). These new compounds have been characterized by elemental analysis, together with FT-IR, H-1 NMR, UV-vis and mass spectral data. Copyright (c) 2006 Society of Porphyrins & Phthalocyanines.