Forming process developed by injection is influenced by rheological characteristics of the feedstock. Because the feedstock is a mixture formed by a powder and a binder, in the performed research it was pursued establishing of binder composition influence. Rheological characteristics establishing was realised with the help of a rotational rheometer RHEOTEST 2, which can be used at the establishing of some properties of Newtonian and non-Newtonian fluids in different temperature circumstances. Utilised binders were formed of different proportions of wax, low density polyethylene, and stearic acid. Obtained results show that wax has a great influence on rheological characteristics of the binder. As it contains increases the dynamic viscosity decreases pronouncedly.