Effect of adding indium on microstructure, wetting process, thermal, electrical and mechanical properties of tin- zinc eutectic alloy have been investigated. Microstructure (started base line, lattice parameters, unit cell volume, crystal size and the shape of formed crystalline phases) and measured physical properties of tin- zinc eutectic alloy changed after adding different ratio of indium content. A little variation occurred in thermo-graph (Endo-thermal peaks) of Sn91Zn9 alloy after adding indium. The contact angle, melting temperature and specific heat of Sn91Zn9 alloy decreased after adding indium content. Also elastic modulus and internal friction values of Sn91Zn9 alloy decreased after adding indium content. But electrical resistivity and Vickers hardness values of Sn91Zn9 alloy increased after adding indium content. The SnZn9In5 alloy has adequate properties for solder applications.