The monolayer and deposition behaviour was investigated for a series of eight 1, 4, 8, 11, 15, 18, 22, 25-octa-alkoxy phthalocyanines. Relative to their metal-free analogues, the copper octapropoxy, copper octabutoxy and copper octapentyloxy phthalocyanines gave larger values for the average area per molecule at a standard surface pressure, showed much reduced hysteresis in the π-A isotherm and exhibited greater monolayer stability. The best deposition onto hydrophilic glass was observed for compounds bearing octabutoxy and octapentyloxy chains. These gave even, green multilayer films by either Y- or Z-type deposition. Films of copper and zinc octapentyloxy phthalocyanines gave X-ray diffraction patterns consistent with domains of layer structuring. The layer thickness was 24 Å for the former and 26 Å for the latter. These values correspond well to the maximum molecular dimension obtained from space-filling models and suggest that, where layer structuring occurs, the molecules are arranged with their planes approximately orthogonal to the substrate surface. The photostability of two examples was investigated.