The optical Kerr effect (OKE) in a transfer ribonucleic acid (tRNA) solution induced by femtosecond pulses of linearly polarized pump light lambda(i) = 800 nm) and sounded by probe light (lambda(p) = 800 nm) was studied. The measurements were performed to find nonlinear optical parameters describing a single molecule (molecular Kerr constant K, mean nonlinear third order optical polarizability c(pi)) and to compare them with our previous OKE results obtained in ns and ps time range. The OKE experiment has proven to be an efficient method to obtain the nonlinear parameters of single molecules in solution, which reflects dynamic structure changes. (C) 2016 Elsevier B.V. All rights reserved.