Stable Isotope Laboratory, established in 2016, at Hyderabad (Headquarters), is an advanced geo-analytical facility for analysis of stable isotopic (C, O and S) ratios in geological materials (rocks and minerals). Isotopic ratios are determined using a gas-source Isotope Ratio Mass Spectrometer (Nu Horizon, NH031). There are three dedicated sample preparation systems attached to the mass spectrometer viz. (i) Nu Carb for the analyses of C and O isotopic ratios in carbonates in dual inlet (DI) mode, (ii) Elemental Analyser (EA) for S and C isotopic ratios in sulphides and organic/carbonaceous matter respectively in continuous flow mode; and (iii) Laser Fluorination (LF) for O isotopic ratios in silicates and oxides in DI mode. The analytical data is used for understanding wide spectrum of geological processes and genesis of mineralisation.