In the arrangement according to the invention for the high frequency coagulation of protein, in particular for surgical purposes, the protein impedance is continuously determined during application of high frequency power and the differential quotient for the impedance curve is formed according to time. The values of the differential quotient serve on the one hand for adjusting the initial power and on the other hand for establishing the optimal time for switching off the high frequency power. For both situations, provision is made for presettings making the arrangement according to the invention flexible and simple to adapt. The arrangement is preferably intended for bipolar coagulation instruments but use with unipolar instruments is also possible.