A systematic quantitative study of the solubility of various naphthalene diimides in apolar and polar solvents with different lipophilicity has been done by means of UV-vis spectroscopy. It has been found that the most soluble naphthalene diimide derivative is N,N'-bis(dehydroabietyl)-1,4,5,8-naphthalene diimide. The conclusion that the introduction of bulky aliphatic substituents is the most appropriate way to improve the solubility of naphthalene diimides has been made. It has been estimated that, in contrast to the case of bulky alkyl substituents, the introduction of bulky aryl substituents does not increase the naphthalene diimide solubility considerably. (C) 2004 Elsevier Ltd. All rights reserved.