Lead-free soldering alloys with low melting point suitable for use in soldering joints are very essential. Use of lead as a solder is considered dangerous for the environment due to the huge number of printed circuit board and electronic devices, pipe joints etc. needed to be recycled from dumps. In this work the metallic samples were prepared from Bi in the mass range from 0.75gm. Samples of Sn were dropped into the bath of pure Bi by using an automatic dropping device. System required 40min time interval after every sample of dropped. Calorimetric measurements was done at temperature 830K. The Integral and partial enthalpy of mixing was calculated at this temperatures. The Integral enthalpy of mixing in Bi- Sn system at 830K is endothermic in nature throughout the composition and its maximum value at Xsn = 0.6, is 1005.9061 respectively.