Citation: Veselý Z., Švantner M., Application of IRNDT method for materials in wide range of thermal diffusivity. NDT.net - e-Journal of Nondestructive Testing (http://www.ndt.net), Vol.22, No.2, 2017, pp. 895-901. ISSN 1435-¬4934. Abstract: Infrared non-destructive testing method (IRNDT) is suitable supplement to classic non-destructive testing methods (NDT). The advantage of IRNDT method is fast and non-contact measurement and evaluation that is available to various industrial and research applications. The method is suitable for both production process inspection (material inhomogeneities, inner structure of multilayer parts, cracks, ...) and subsequent component inspection during service (cracks, layers delamination, etc.) The possibility of defects detection is influenced by IRNDT method parameters, geometric orientation of defects and by physical properties of material. The influence of material thermal properties on the detectability of defects is discussed.