Blasts and detonations release large amount of energy in short time duration. Some of this energy is released through radiation in the whole optical spectrum. Measurement of the blast signature may serve as a powerful approach for investigation of blast phenomena. IARD had developed a fast multispectral radiometer that operates in the proper spectral bands to provide extensive information on the physical processes that govern the blast. This information includes the time dependence of the temperature, area, composition of aerosols and gases in the blast flash. Analysis of the blast signature provides indications on the order of the detonation, materials and masses of high-explosives and casing. This presentation will describe the methodology and instrumentation of fast multispectral radiometry in application to the blast signature measurement and analysis in a near-ground explosion test where the radiation of two high-explosive (HE) materials (TNT and composition B - CB) with wide range of mass and casing materials was investigated.