Cathodic tafel constants associated with the hydrogen reaction at fe18cr in h2-saturated 1nh2so4 were determined by computer analysis of the potential decay following current interruption at fixed starting potentials positive to the corrosion potential. The values of b = -2.3 Rt/af were evaluated from the general current- interruptive equation, e = e1 + b.Log [1 + t/n], from its linear log form, and from a modification of the general equation that was derived to analyze multiple tafel regions. For starting potentials of 0, -0.05, -0.075, and -0.2V (rhe), the number of tafel regions was 3, 3, 2, and 1, respectively. The amount of hydrogen associated with the electrode at the fixed potentials and during decay was determined from anodic charging pulses. Results indicated that the bonding strength betwen metal sites and hydrogen varies with decay and starting potential. The first tafel region from 0, -0.05, and - 0.075V was under combination control, 2h->h2. The decay from -0.2V was controlled by the electrochemical-desorption step, h+ + e + h- >h2.