Active damping in a smart cylindrical shell using piezoelectric sensors/actuators is studied. The electrodes on the sensors/actuators are spatially shaped to reduce spillover between circumferential modes. A three-noded, isoparametric, semianalytical finite element is developed and used to model the cylindrical shell. The element is based on a mixed piezoelectric shell theory that makes a single layer assumption for the displacements and a layerwise assumption for the electric potential. The effects of axial and circumferential mode number, length to radius ratio, radius to thickness ratio of the shell, percentage of the area of the shell covered with piezoelectric material, and the location of the collocated sensor/actuator on the shell on the active damping ratio of the shell are studied. © 2000 Sage Publications, Inc.