The advances in two dimensional array detector technology in the optical and near infrared wavelength bands have made new kinds of imaging astronomical observations feasible. Astronomical polarimetry is one field which has gained tremendously from these developments. The limitations of using aperture photometry for polarimetry were so severe that any serious study was rendered time consuming and difficult. On the other hand, imaging polarimetry with its capabilities for multiplexing, simultaneous sky measurement, seeing-limited resolution etc. offer great advantages over aperture polarimetry. Astronomers have recognized this potential and have developed several new observational techniques in the optical (e.g. Scarrott 1991; Jannuzi et al. 1993; Jarrett et al. 1994; Wolstencroft et al. 1995; Simmons et al. 1995) and near infrared (e.g. Kastner & Weintraub 1994; Moore & Yamashita 1995; Weintraub et al. 1995) wavelengths to study phenomena in a variety of Galactic and extragalactic astrophysical objects. In this paper, we report the design and construction of an imaging polarimeter (IMPOL) which uses a cooled CCD array as detector. It was developed at the Inter-University Centre for Astronomy and Astrophysics , India. The principle of the instrument (Sen & Tandon 1994) is based on a combination of ideas suggested by Ohman (1939) and Appenzeller (1967). An instrument of this type has been constructed at the University of Durham and has been in use for some time now (Scarrott et al. 1983). Section 2 is a description of the instrument - the different subsections dealing with various aspects ranging from design guidelines to instrument control and user-interface. The dominant sources of errors in the measurement are investigated in Sect. 3, while an estimate of the performance of the instrument under two typical observing conditions is given in Sect. 4. In Sect. 5 we discuss the observational procedure and the data-analysis method. Section 6 contains results obtained during commissioning of the instrument. The last section (Sect. 7) contains a summary.