High temperature superconductor (HTS) thin films can be used to construct microwave devices such as filters and antennas with superior performance. We show how the films can be manufactured using a sol-gel method which has the advantage of being able to produce large area films quickly, at low cost on simple equipment. We have developed a sol-gel precursor which has the additional benefits of using commonly available non-toxic reagents, and which can be prepared quickly. High T-c and high J(c) films have been made with this precursor. These films can be patterned to make microwave filters with better sensitivity and selectivity than conventional filters. A design for a microstrip layout of a quasi-elliptic bandpass filter which can be implemented on a 10 mm x 10 mm film is described. Simulated results comparing filter implementations with metal and superconductor films operating at 77 K are given. (C) 2003 Elsevier B.V. All rights reserved.