A combination of 1D and 2D NMR techniques, including HMQC, HSQC, ¹H-¹H COSY and HMBC, was used to provide completely assigned ¹H and ¹³C NMR data for the structures of three 3-[substituted methylidene]-1H,3H-naphtho[1,8-cd]-pyran-1-ones—3-[(4-methoxyphenyl)methylidene]-1H,3H-naphtho[1,8-cd]-pyran-1-one, 3-[(4-fluorophenyl)methylidene]-1H,3H-naphtho-[1,8-cd]-pyran-1-one and 3-[(thiophen-3-yl)methylidene]-1H,3H-naphtho[1,8-cd]-pyran-1-one. The heteronuclear coupling constants ^1–4J_CF and ^3–4J_HF were correspondingly determined. Additionally, IR and Raman spectral data were provided in support of the assigned structures.