A 3D generalization of van Kampen's 1D model describing relativistic heat transport is derived and discussed in detail. As in the original model, the complete solution has finite speed of propagation while its long-time asymptotic satisfies the classical Fourier equation. A 3rd order diffusion equation is found. Compared to its 1D counterpart, it contains an extra mixed-derivative term. (C) 2012 Elsevier Ltd. All rights reserved.