The shear strength and volume change behavior of an unsaturated non-plastic silty soil is determined with a high suction value using a relative humidity controlled triaxial shear testing apparatus. The design details of this apparatus are briefly presented in this paper. The results of the undertaken study suggest that the Fredlund et al. 1978 equation can be used for interpreting the shear strength behavior of unsaturated soils in the high suction range. In addition, a technique is also presented to determine the volumetric deformation coefficients in loading and unloading stages respectively at high suction values.