An electronic arrangement for determination of reactive power, including two transducers delivering at their outputs measuring voltages proportional to supply current and supply voltage. An additional phase shift of 90.degree. between the two measuring voltages is produced by phase-shifting elements. A signal proportional to reactive power is produced in a following multiplier element. To preclude as far as possible variation of amplitude and phase shift occurring on frequency fluctuation in a frequency range close to rated frequency of the power supply, an all-pass is connected as a phase-shifting element ahead of each of the two respective inputs of the multiplier element whereby one all-pass is designed to produce a phase shift of +45.degree. and the other all-pass is designed to produce a phase shift of -45.degree. at the rated frequency of the power supply.