Quantum tomography is a widely applicable tool for complete characterization of quantum states and processes. We develop a method for precision-guaranteed quantum process tomography. With the use of the Choi–Jamiołkowski isomorphism, we generalize the recently suggested extended norm minimization estimator for the case of quantum processes. Our estimator is based on the Hilbert–Schmidt distance for quantum processes. Specifically, we discuss the application of our method for characterizing quantum gates of a superconducting quantum processor in the framework of the IBM Q Experience.