© 2020 TIBTD Printed in TurkeyIn this study, the contribution of phonon to the thermal conductivity in the In-Bi (Indium-Bismuth) system due to its composition variation was determined from their electrical and thermal conductivity measurements. Because of the common usage of In-Bi system in many technological applications, thermal and electrical conductivity variations with temperature for different compositions of Bi component were measured. Four-Point Probe (FPP) and Linear Heat-Flow (LHF) methods were used for electrical and thermal conductivity measurements respectively. Intermetallic systems' electrical conductivity values were determined between 0.8524 (1/Ω m) ×106 and 2.8381(1/Ω m) ×106 and thermal conductivity values were found between 14.50 (W/Km) and 35.93 (W/Km) at the melting temperature. Electron and phonon contributions to the thermal conductivity were calculated by using Wiedemann-Franz Law (WFL) from the measured values. The temperature coefficients values (a) of electrical and thermal conductivity were calculated between 0.46-2.54 (K-1) x10-3 and 1.29-4.34 (K-1) x10-3 respectively. In order to observe microstructure of the Bi-In intermetallic alloy Scanning Electron Microscopy (SEM) and to determine the composition of the phases in the structures, Energy Dispersive X-Ray Analysis (EDX) were used. Also melting temperatures (349.03 K-387.24 K), enthalpy of fusion (17.97 J/g- 42.37 J/g) and specific heat change (0.159 J/gK-0.372 J/gK) of Bi-In alloy systems were measured by using Differential Scanning Calorimeter (DSC).