This study aimed to investigate the intermediate and high temperature performance characteristics of asphalt cement (AC) modified by iron-oxide nanoparticles (ION). Moreover, Fuzzy PROMETHEE-II technique was employed in order to evaluate the performance of base and ION modified AC by considering multiple criteria; physical properties, rheological characteristics, durability and economic aspects. Excluding the control sample (base AC); three different blends that contained 1%, 3% and 5% ION by the weight of AC were prepared. By conducting rheological testing procedures, isochronal plots were constructed and rutting and fatigue resistance parameters were evaluated. In addition to rheological properties, physical properties were also investigated under unaged and aged conditions and they were utilised in the Fuzzy PROMETHEE-II analysis. According to the experimental outcomes, the optimum concentration of ION was found to be 1% by the weight of AC at high temperatures and above this concentration the improvement of viscoelastic behaviour was hindered to due agglomeration. In other respects, addition of ION in the AC resulted in degrading of the elastic properties, meaning lower fatigue resistance against cracking. The findings of Fuzzy PROMETHEE-II also demonstrated similar trend of results with minor deviations indicating that, not only considering a single parameter but also as a complete ranking evaluation considering multiple criteria, the findings of the current study were reinforced.