The stable isotope geochemistry of molybdenum, a highly redox-sensitive element, is poorly known due to the lack of a suitable method to correct for instrumental mass-dependent isotopic fractionation. I worked with Mo isotopic data retrieved from a multiple collector inductively coupled plasma mass spectrometer (MC-ICP-MS) to find a precise and accurate method to correct for the effects of instrumental mass-dependant isotopic fractionation. Several correction methods used on the same data from Mo isotopic standards were compared (inter-element, sample-standard bracketing, and graphical). The sample-standard bracketing method is shown to provide a more precise correction than either the inter-element or graphical methods. To further test these correction methods, I applied each method to Mo isotopic data collected from MoS2-bearing ores that formed under a range of redox conditions. Overall, the sample-standard bracketing method of correction also improved the precision of replicate MoS2 analyses compared to the other methods. These MoS2 samples display a 1.4%0 range of Mo/95Mo, which is larger than the 0.4%0 range found in previous studies. These preliminary results suggest that Mo may be isotopically heavier in reducing ore systems compared to oxidizing ore systems, but more data is needed to test this hypothesis. The results of this project will improve our ability to study mass-dependant Mo isotopic variations in nature.