The present work investigates by electrochemical and steady-state and time-resolved spectroscopic methods a synthesized compound 5-nitro-benzo[b]thiophene-2-carboxylic acid (5NBTC), both in normal solvents and in the presence of TiO 2 nanoparticles to reveal the nature of the photophysical processes involved. From the present experimental observations it is inferred that both in the ground state and the excited electronic state S 1 , there exists a strong binding between –COOH functionality of 5NBTC and TiO 2 nanoparticles. However, the rupture of this binding in the presence of excess TiO 2 , as apparent from the steady-state and time-resolved spectroscopic measurements, is responsible for the increase in radiative transitions. Formations of aggregations of TiO 2 nanoparticles at higher concentrations appear the cause of such rupturing. The redox potential measurements by cyclic voltammetry and theoretical computations by time-dependent density functional theory (TD-DFT) with B3LYP/6-311 G(d,p) basis function implemented in the Gaussian package confirm the electron accepting nature of 5NBTC and hence no electron transfer is possible between the organic compound and TiO 2 nanoparticles. It is most likely that the interaction model between 5NBTC and TiO 2 nanoparticles should be that the –COOH group of 5NBTC molecule coordinates either directly or through a hydrogen bond to the TiO 2 surface.