High responsivity detection (≳1 KV/W) of 9 GHz microwave radiation by high temperature superconducting films has been observed around 60 K. Measurements were made on YBaCuO film deposited on MgO substrates. The responsivity is related to the strongly nonlinear current‐voltage characteristics of these films and the films behave like an SNS junction. We discuss the characteristics of the observed detection mechanism, its physical origin and potential applications.