Three layered clothing assemblies were constructed from commercial heat protective textile clothing materials for outer, middle and inner layers. Thermal liners, used as middle layer, were prepared from Nomex fibres of two different fineness keeping other parameters constant. Different three layered combinations of fabrics were compared for radiant heat protective performance based on the estimate of burn injury time using Stoll’s curve. Analysis of experimental results showed that characteristics of the outer layer fabric and its interaction with applied heat flux are important factors that affect thermal response of the clothing assemblies. Fineness of the constituent fibres of nonwoven thermal liner was found to significantly affect the protective performance. Thermal properties, porosity, optical properties of the clothing layers found to affect heat protection provided by clothing assembly.