In the present work ternary chalcogenide p-type semiconductor Zn1-xFexS has been prepared by co-precipitation method for x = 0.18 and 0.4 concentrations of Fe. The precipitate was repeatedly sintered at 800degreesC in sealed quartz ampoules for a total of 165 h The material was then characterized by X-ray diffraction, X-ray fluorescence (XRF), EDAX, EPMA, diffuse reflectance spectroscopy, thermoelectric, electrochemical and capacitance measurement techniques. Compositional analysis techniques, viz. XRF, EDAX and EPMA reflected the composition of the solutions from which precipitation was carried out while X-ray reveals a sphalerite crystal structure. Capacitance measurements indicate that the relaxation effects are enhanced with increasing Fe substitution. Thermoelectric measurements indicate p-type conductivity in agreement with the results obtained by electrochemical analysis. The flat band potential V-fb has values 2.94 V (x = 0.18) and 2.66 V (x = 0.4) as obtained by Mott-Schottky plot. Similarly the optical band gap was found to decrease with increase in Fe concentration. (C) 2004 Published by Elsevier B.V.