The complete lateral distributions of emitted intensity and optical thickness of the instationary plasma column are measured simultaneously by probing the plasma with its own radiation and recording both distributions on a single high-speed spectrum. From these lateral distributions the radial distributions of the coefficients of emission and absorption are calculated and by application of Kirchhoff’s law the radial temperature distribution is determined. This new technique has been applied to an exploding wire plasma with 37 000 K on the axis. The mean deviations of three temperature distributions obtained by independent measurements at different wavelengths are less than 3 per cent.