The necking of specimen is specifically related to the decrease in cross section when specimen is subjected to tensile strength greater than ultimate tensile strength (UTS). The strain distribution no longer hold uniform along the gauge length. As the tensile load is applied, due to which length of specimen increases but there is decrease in cross section. The present work laid stress on determining the tensile properties from stress strain curve by tensile testing of aluminium (specimen) at different range of high temperature The tensile testing is carried out on INSTRON static series 600 KN. The specimens were tested at different range of high temperature (Room Temperature -325 degree Celsius). True Stress and strain is calculated using the engineering equation. Using the values of true stress and true strain the true stress strain curve was plotted. The polynomial equation is obtained from each specimen curve. The graph is plotted between temperature and ultimate tensile strength (UTS) which indicates that the ultimate tensile strength decreases with the increase in temperature.