Peanut crop is exposed to both mid-season and end-season water stress that coincide with flowering and pod development. The objective of this study was to investigate genotypic variability for water use efficiency in response to water and high temperature stress. The experiment consisted of a factorial combination of three water stress treatments (D1 – irrigated to maintain field capacity (FC, where the available soil moisture (ASM) is 100% at field capacity) throughout the study; D2 – early water stress (40% ASM) from flowering to pod initiation; and D3 – late water stress (40% ASM) from pod initiation to harvest), two temperature treatments (T1 - optimum temperature of 28/22ºC (day/night); T2 - high temperature of 40/22ºC(day/night) and two genotypes (ICG 796 and ICGV 86015). Each treatment combination was replicated four times. Water use was modified differently in the genotypes by both temperature and water stress treatments. Among the genotypes, ICG 796 recorded higher WUE than ICGV 86015. Early water stress (D2), from flowering to pod initiation, reduced WUE by 52%, while late water stress (D3) imposed from pod initiation to harvest resulted in a 39% decrease in WUE. High temperature effects on WUE were significant only at final harvest. Water stress reduced groundnut yields in this study by having detrimental effects on both source and sink production, and also by delaying development.