The pyroelectricity and crystallization level of yttrium barium copper oxide (YBa2Cu3O6+x) thin films have been investigated by depositing the thin films by rf magnetron sputtering at different substrate temperatures. A portion of the thin film samples were analyzed by x-ray diffraction (XRD) to investigate the crystallinity while the remainder were processed to fabricate capacitor structures with Au electrodes to study the pyroelectric properties of the thin films. We observed different crystallization levels for samples that were deposited at different substrate temperatures. Pyroelectric behavior was observed to be correlated to the strength of the XRD peaks observed. Samples that lack crystallinity did not display pyroelectric behavior, while samples with observable crystallinity displayed pyroelectric behavior, either as deposited without poling or induced by poling. Samples lacking crystallinity could not be poled to display a measurable pyroelectric behavior. Pyroelectric coefficients on the order of 50 nC/K cm2 were observed in the polycrystalline samples. © 2003 American Vacuum Society.