YBa2Cu3O6+x (YBCO) oxides, well known as superconductors for x > 0. 5, are semiconductors (SC) for lower oxygen content. SC films DC sputtered at 150 °C in amorphous form (a-YBCO) exhibited a temperature coefficient of resistance competitive with other bolometric sensing materials. Such deposition conditions are highly beneficial to integrate a radiation detector on a silicon chip bearing already processed readout electronics. IR detector structures have been processed: simple planar or more advanced metal/a-YBCO/metal trilayers. IR response was investigated at 850 nm as a function of the modulation frequency. The planar structure exhibited a regular bolometric response below 100 Hz, then a pyroelectric high-pass response up to 100 kHz. The trilayer device only exhibited the pyroelectric behavior up to 100 kHz . In the pyroelectric regime, detectivity values peaked above 2×108 cm Hz½/W with time constants in the μs range, under both DC biased and unbiased conditions.