The Sn-58Bi (SB) lead free solder alloy tested in this research with addition of 3% Molybdenum (Mo) nanoparticles equivalent to 0.6g mass to analyse the influences in the thermal, microstructure and microhardness. Elevation of 3.8°C was observed from the Differential Scanning Calorimetry (DSC) for the 3% Mo nanoparticles added SB solder alloy compared to the bare Sn-58Bi (SB) solder alloy that has a melting temperature of 142.25°C. The microstructures of the reinforced SB solder alloy were refined with closer lamellar structures of ?-Sn and Bi phases compared to the unreinforced SB solder. The SEM/EDX and X-ray Diffraction (XRD) results validate the presence of the 3% Mo nanoparticles in the SB solder. Mechanical properties by means of Vickers microhardness of the Mo reinforced solder alloy showed an increment in hardness value by 2% compared to the bare SB solder alloy. The presence of 3% Mo as discrete particles (dispersion strengthening) contributes to the increase on the hardness value. The introduction of 3% Mo in to the SB solder alloy resulted in increase in the hardness due to the refinement of the microstructure and at the same time allows low temperature soldering in the electronic packaging industry.