Single phase (gamma and beta) barium borate with nanorod structures were prepared by hydrothermal method at reaction conditions of 433 and 1073 K respectively. FESEM images demonstrated the transformation of nanoclusters into elongated nanorods as the reaction time increased. The third order nonlinear optical (NLO) properties of the samples were investigated by the Z-scan technique (800 nm, 150 fs, 100MHz). Both phases of barium borate depicted nonlinear absorption and was assigned to the two-photon absorption mechanism. gamma-BBO demonstrated negative nonlinear refraction (self-defocusing) while beta-BBO showed positive nonlinear refraction (self-focusing). Both the phases exhibited optical limiting behavior and the limiting threshold was found to be in the order of mu J/cm(2). Nanorods possessed superior third order NLO coefficients compared to nanoclusters of barium borate. Also gamma-BBO possessed superior NLO properties compared to beta-BBO and it can be strongly emphasized that gamma-BBO nanorods can be used as a potential material for photonic applications. (C) 2016 Elsevier Ltd. All rights reserved.