The hyper-Rayleigh scattering (HRS) method was employed to investigate the first hyperpolarizability (beta) of a triindole derivative with dicyanovinyl groups (TDCV). Because TDCV showed fluorescence due to two-photon absorption, we tried to precisely determine the beta value of TDCV by observations of spectra composed of the HRS light and fluorescence and deconvolutions of the HRS light and. uorescence components with a slit function. Moreover, we tried to determine the depolarization ratio of the HRS light from TDCV by polarization measurement. As results, we have found that the beta value of TDCV is (319 +/- 13) x 10 (30) esu at 1070.0 nm and TDCV can be classified as a purely octopolar molecule with the C-3h symmetry. (c) 2008 Elsevier B.V. All rights reserved.