This study investigates the effects of temperature, time, and concentration of nitric acid passivation solutions on the properties of oxide films formed on medical grade 316L stainless steel. Passivation with solutions of varying nitric acid concentration (21, 28, 35, and 42%) was carried out at three temperatures (22, 50, and 80 degreesC) for three different time periods (10, 30, and 60 min). Effectiveness of passivation was estimated by determination of the Cr/Fe ratio of the surface oxide films from XPS, and the highest temperature provided the greatest Cr/Fe values while changing passivation time and nitric acid concentration had minimal effect. Although oxide films on stainless steel are intrinsically very thin, depth profiles showed that the highest passivation temperatures produced the thinnest oxides. Surface morphology and roughness were evaluated by SEM and AFM. Finally, time between electropolishing and passivation was varied, and Cr/Fe gradually increased with increasing time interval up to 24 hours. When the metal was immersed in deionized water for 24 hours, Cr/Fe increased by >50% over that allowed to dry.