Weight change behavior of fiber-reinforced polymer composites in humid and thermal environments appears to be a complex phenomena. The weakening often appears at the interface during state of fiber/matrix interface is believed to influence the nature of diffusion modes. A significant weak the hygrothermal ageing. It effects the moisture uptake kinetics and also the reduction of mechanical properties. The importance of temperature at the time of conditioning plays an important role in environmental degradation Of Such composite materials. An attempt has been made here to evaluate the deleterious effect of temperature oil shear strength of carbon/epoxy and glass/epoxy composites during hygrothermal conditionings. Mechanical tests were conducted at room temperature to assess the effectiveness of the relaxation process in the nullification of environmentally induced damage in the composites. (c) 2005 Elsevier Inc. All rights reserved.