ABSTRACT In the present work, nodular cast iron (NCI) was austenitised at 1173 K (900°C) for 2 h followed by quenching and subsequently tempered at a temperature ranged from 523 K (250°C) to 923 K (650°C) in 100 K (100°C) increments for 1 h, 1.5 h and 2 h, respectively, to investigate the microstructure and mechanical properties of the material. These heat treatments control the rate of austenite to pearlite transformation and the size of second-phase particles that greatly influenced the mechanical properties of the material. The study of tensile properties reveals that with varying tempering temperature from 523 K (250°C) to 923 K (650°C), ultimate tensile strength (UTS) value initially increases, reaches to maximum and then decreases. At particular tempering temperature with increase in tempering time, the UTS, hardness and impact strength decrease. The optimum mechanical properties (UTS~1040 MPa, El~2%, Impact Toughness~9 J) were obtained at the tempering temperature of 723 K (450°C) with the tempering time of 1.5 h. Fractured surfaces observed using a scanning electron microscopy indicate the significant influence of different tempering conditions on the mode of the failure of NCI.