We outline the construction of compatible B-splines on 3D surfaces that satisfy the continuity requirements for electromagnetic scatter- ing analysis with the boundary element method (method of moments). Our approach makes use of Non-Uniform Rational B-splines to rep- resent model geometry and compatible B-splines to approximate the surface current, and adopts the isogeometric concept in which the basis for analysis is taken directly from CAD (geometry) data. The approach allows for high-order approximations and crucially provides a direct link with CAD data structures that allows for efficient de- sign work ows. After outlining the construction of div- and curl- conforming B-splines defined over 3D surfaces we describe their use with the electric and magnetic field integral equations using a Galerkin formulation. We use Bézier extraction to accelerate the computation of NURBS and B-spline terms and employ H -matrices to provide ac- celerated computations and memory reduction for the dense matrices that result from the boundary integral discretization. The method is verified using the well known Mie scattering problem posed over a perfectly electrically conducting sphere and the classic NASA almond problem. Finally, we demonstrate the ability of the approach to han- dle models with complex geometry directly from CAD without mesh generation.