Brivanib is an oral dual inhibitor of VEGFR and FGFR tyrosine kinases. Brivanib inhibits FGF-stimulated and FGF-dependent cell lines. During the synthesis of its penultimate, an impurity at 0.18% level with MW 517 Da was observed in HPLC profiles. In order to control the formation and prevent its possible conversion to the corresponding impurity in the next step of the synthesis to form the API, its structure information was needed. In this presentation, we report the isolation and comprehensive spectral characterization of this impurity using HPLC, LC/MS and one and two-dimensional NMR techniques such as 1H, 13C, DEPT, 2D-COSY, 1H-13C HMQC and 1H-13C HMBC, and 1H-15N HMQC and 1H-15N HMBC. Rationale for the formation of this impurity and how to control its formation are also presented.