The Lattice Boltzmann method (LBM) is a collision based computational fluid dynamics method used as an alternative to more traditional finite difference and finite element methods, in that LBM is built to take advantage of parallel systems. In the present case, LBM is used to model three-dimensional transient conjugate heat transfer within a box containing a solid fin. A comparison of different implementation methods for conjugate heat transfer has been carried out to determine their applicability. The geometry modelled was input as a stereolithography file, which may be generated easily by a range of packages, such as SolidWorks. From the simple box and fin geometry trialed, the solution method can easily be adapted to evaluate the suitability of structured packings for packed bed reactors, or other solid-fluid systems.