An improved low Reynolds number k(theta)-<(epsilon)over tilde>(theta) turbulence model is proposed to model the thermal field without the explicit prescription of the turbulent Prandtl number. The model is designed to conform with the near-wall characteristics obtained with direct numerical simulation data, but also to possess correct asymptotic behavior in the vicinity of the wall. The asymptotic limits of equations, governing the temperature variance (k(theta)) and its dissipation rate (<(epsilon)over tilde>(theta)), are satisfied by the incorporation of the viscous dissipation related terms. The performance of the proposed model is evaluated by applying to fully developed channel flows with and without wall transpiration, and the thermal entrance region of a duct. The computations are validated against measurements and direct numerical simulation data and the predicted results indicate that the proposed model is capable of reproducing the complex near-wall thermal field considered.