This paper reports the fabrication of microbolometers using semiconducting YBaCuO as the IR sensing material. The detectors are operable at room temperature and thus are suitable for last-cost and high performance imaging applications. Semiconducting YBaCuO is promising as a bolometric material as it has a thermal coefficient of resistance near 3% and relatively low noise. Two different bolometer structures will be reported here. First generation YBaCuO microbolometers were built on micromachined SiO2 bridges using wet etching techniques to undercut the silicon. The second generation structures were processed upon micromachined Si3N4 membranes with sputtered MgO films used as sacrificial layers. The membrane structures are the first of its kind to incorporate MgO as a sacrificial layer, and they offer a fabrication technique that is fully CMOS compatible, with all processing at ambient temperatures. Detectivities in the order of 10(8) cm Hz(1/2)/W were measured at 30 Hz chopping frequency in both structures. The thermal conductance of the suspended membranes was on the order of 10(-7) W/K, which is desirable as low thermal conductance yields high responsivities. There are realizable optimizations for both applications to yield detectivities over 1.0(9) cm Hz W-1/2. All measurements reported here were performed at ambient temperature with no temperature stabilization.