In this work the similarity solution of the thermal boundary layer for a laminar axisymmetric jet with viscous dissipation is derived and solved numerically, using a fourth-order Runge-Kutta method. The results are compared with the existing solutions, in which viscous dissipation is neglected. After that the effects of Reynolds and Prandtl numbers of the incoming hot jet on the temperature profile of the jet is investigated. It is seen that inclusion of viscous dissipation term results in a more rapid heat exchange between the incoming jet and quiescent fluid than the case where the viscous dissipation term is neglected. Also, it is observed that by increasing the Reynolds and Prandtl numbers of the jet, the heat penetrates better in locations near the symmetry line, whereas in locations farther from the symmetry axis the penetration is less.