A superconducting critical temperatureTchas been measured inductively on aninsitu‐formed Nb3Sn wire. The measurement has been carried out by varying the amplitude and frequency of the applied alternating magnetic field in the range from 0.001 to 100 G and from 0.2 to 100 kHz, respectively. It has been found that the normal to superconducting transition is dependent on the amplitude and slightly dependent on the frequency of the applied field.