When applying laser transformation hardening (LTH) on a steel part the aim is to harden a localized area, which results in high hardness value for a defined width and depth of the material. To assure the hardened zone and keep the maximum temperature of the surface below the melting point we have used a finite element model (FEM) to compute the solution for heat distributions and the phase transformation of the material during LTH. Modelling results were used to introduce safe operating regions for LTH with different processing conditions. A problem associated with some LTH applications is the necessity to overlap the hardening passes. The temperature distribution of this phenomenon was also modelled using FEM which truly assist in finding optimum overlapping and technological parameters.