In this study, the rheological characteristics of the feedstocks produced from steatite powder and from 316L stainless steel powder with polyethylene glycol (PEG) based binders have been investigated. The suitable temperature and pressure conditions for feedstocks have been determined for powder injection moulding (PIM). Five different binder compositions have been used in this research. PEG was the main constituent of each binder. The constituents of the binders are PEG 3000 and PEG 8000, high density polyethylene (HDPE), polypropylene (PP) and stearic acid (SA). The feedstocks produced from steatite powder (45-60 vol%) and from 316L (60-70 vol%) have been tested in a capillary rheometer. It has been concluded that for PIM, the critical powder ratios for the steatite powder and 316L were 53% and 66%, respectively. For steatitebased feedstocks, the shear rates were changed within the range of 65-4093 s-1 and the viscosities were changed within the range of 20-1722 Pas. For 316L-based feedstocks, the shear rates were changed within the range of 119-185 s-1 and the viscosities were changed within the range of 319-494 Pas. It has been observed that the viscosity is shear-rate dependant in both feedstocks with pseudoplastic behaviour.