Human interferon gamma (hIFN gamma) plays a key role in the immune system and therefore this cytokine has many current and future therapeutic applications. hIFN gamma is well known with its aggregation propensity and despite its clinical use, there is not much data about the stabilization of hIFN gamma preparations. Nowadays, substantial evidence indicates that the pathogenesis of many autoimmune diseases is related to overproduction of hIFN gamma. In this regard we have developed inactive hIFN gamma analogues to act as receptor antagonists of the endogenous hIFN gamma. Since they show even higher tendency for aggregation than the wild type protein, we designed two-step thermofluor screen of 61 buffer conditions to identify the best storage solution for all investigated proteins to be used in the form of research samples or biopharmaceuticals. Tris buffer pH 8.0 supplemented with NaCl and trehalose/betaine/glycerol as additives showed to be the most appropriate choice ensuring high solubility and thermal stability of both hIFN gamma and its mutants.