A new computer code has been developed with the capability to model laminar liquid metal fluid flow and heat transfer in relatively complex geometries at parameter values greater than previously possible with a transient 3-D “full” numerical solution of the MHD equations. The full solution method, which includes viscous and inertial terms, provides an exact solution for boundary layers and is valid over a wide range of flow parameters. Previous attempts at numerically solving the full MHD equations have been limited in the range of magnetic field strengths (B) and Reynolds number (Re) which could be accurately modelled. Numerical techniques for treating problems at high B and Re are implemented in this code, named KAT. The KAT code is written in rectangular coordinates, with a sophisticated mesh generator and boundary condition input routines. Single-duct and multiple-duct geometries can be modelled with arbitrary wall conductivity and magnetic field variation throughout the solution domain. The code has been tested and benchmarked against analytical solutions and fully-developed very highly accurate numerical solution obtained by 2-D finite element method (FEM). The KAT solutions are in very good agreement with analytic and FEM solutions. The KAT code was applied to a right-angle rectangular bend problem with inclined B-field. Finally, the capabilities of the code and future applications are discussed.