Flow stress functions which describe the behavior of materials during hot deformation have been used to model forming processes. In order to predict the flow stress of the bulk and sheet materials and interfacial friction between workpiece and tools under hot working conditions, a new function has been proposed and an inverse analysis technique has been introduced. The inverse problem is defined as the minimization of the differences between the experimental measurements and the corresponding FEM predictions. This function can be applied to determine forming loads, strain-rates, strains and deformation features in several temperatures. Compared with earlier works, predicted deformation behavior of materials had the good agreements. Using them, it was confirmed that it is possible to predict the kinetics of dynamic recovery and recrystallization utilizing inverse analysis without the approach of microstructural aspects. It is shown that the developed inverse analysis technique is reliable and can determine the flow stress and interfacial friction simultaneously from one set of material tests.