The present study presents a theoretical model for the laser gas-assisted cutting mechanism which includes the chemical reactions, momentum and assisting gas effects as well as that of conduction and convection. A heat-transfer model based on a boundary layer consideration has been adopted. In the analysis the relationship between the various parameters including power intensity, material thickness, gas jet velocity and cutting speed are predicted. A quantitative measure of chemical reactions between the molten and the assisting gas, evaporation of metal and the cooling effect of the gas jet are taken into account. The turbulent boundary layer over the molten metal is considered. An experiment is carried out to measure the cutting speed with different settings of laser power intensity. This provides a comparison between the theoretical predictions and experimental results. The experiment is extended to include monitoring of the initial plasma formation during the cutting operation. This enhances the understanding of the oxygen effect and initiation of the cutting process.