To investigate the quasiparticle dynamics in the superconducting state of quasi-two dimensional heavy fermion superconductor CeCoIn5, thermal conductivity tensor is measured. We obtained the quasiparticle mean free path and the density of states separately by using the combination of longitudinal thermal conductivity and thermal Hall angle. The quasiparticle mean free path increases dramatically below T-c in zero magnetic field. The density of states and the scaling relation of thermal Hall conductivity are consistent with d-wave symmetry. We also argue that CeCoIn5 is in the superclean regime. These results highlight the anomalous superconducting state in CeCoIn5 with striking similarities with high-T-c cuprates. (c) 2006 Elsevier B.V. All rights reserved.