Abstract: The invention relates to a signal processing method and apparatus for nuclear spectrometers, whereby the peaking time is set, which is optimal from the point of view of the signal-to-noise ratio, where in case of an input signal of staircase shape modulated with noise, the so called base-line filtering interval preceeding the actual signal and the signal filtering interval following the actual signal are chosen so that their widths are equal to the width of the optimal peaking time (T.sub.p), the momentary value measured in the base-line filtering interval (A.sub.i) is subtracted from the momentary value measured in the signal filtering interval (J.sub.i), where said momentary values (A.sub.i and J.sub.i) are measured in the time scale symmetrically with regard to the rising edge of the signal, and the differences (J.sub.i -A.sub.i) are summed with weighting factors (W.sub.i).