Abstract The syntheses of α,ω-di-2-pyrenyl- and α,ω-di-2-fluorenylpolyenes In and In′ (n=1–6) by means of the Wittig reaction are described. Aldehydes II, II′, propenals IV, IV′, pentadienals V, V′ bearing 2-pyrenyl or 2-fluorenyl terminal group and muconaldehyde VI were used as carbonyl components. Phosphoranes III, III′, VII, VII′, VIII and VIII′ were prepared from methyl-, propenyl-, and pentadienyltriphenylphosphonium bromides substituted with 2-pyrenyl or 2-fluorenyl group by the reaction with phenyllithium. In and In′ were obtained by the reaction of carbonyl components with phosphoranes by proper combination. It was found that the bathochromic shift of the longest-wavelength peaks of In and In′ can be expressed by the following empirical equations: & I_n:λ=44.6n^0.7+314 (nm in tetrahydrofuran) & I_n’:λ=29.5n^0.8+353 (nm in tetrahyhrofuran)