Composites can fail due to exposure to certain corrosive environments such as water, aqueous acids and bases, and organic solvents. The objective of this study was to determine the interlaminar shear strength (ILSS) and impact property changes on unidirectional carbon fibre reinforced polyetherimide (PEI) composites following exposure to various liquid environments at ambient and elevated temperature. The sample weights were increased for both of the samples with swelling effect. From the detailed investigation of the impact energies, it was observed that the crack initiation energy was decreased while the propagating energy was increased. Liquid environments with higher temperature affect material more remarkable compared to lower temperature. Also, remarkable decrease in ILSS values for all samples subjected to liquid environments was observed. By means of scanning electron microscope (SEM) studies the fracture mechanisms and morphology of the material after chemical corrosion was investigated. Remarkable morphological changes at the cross section of treated materials were observed. (c) 2006 Springer Science + Business Media, Inc.