Abstract: The main objective of these experimental investigations is to correlate the results of vibration analysis and spectroscopic studies of degraded grease in assessing the surface wear of outer race of the roller bearing. Fourier Transform Infrared Radiation (FTIR) is adopted to observe degradation of grease with running hours. Kurtosis value is computed from time domain signals captured to find out progressive wear in the bearing. It is found in FTIR spectrum of 450 h aged grease sample that an absorbance peak occurred around a wavelength of 1750 cmG1 which indicated the formation of oxidation products. Further, at 1000 h FTIR spectrum indicated that there is formation of phenyl group and degradation of anti-wear agents of grease samples as evident by an absorbance peak at 717 cm^–1. Analysis of time domain signals revealed that kurtosis values increased for the bearing at1000 h of run compared to that of healthy bearing. A maximum bearing temperature of 700°C occurred after 1000 h of run as depicted by temperature indicator. Further, SEM morphology of bearing surfaces illustrated wear tracks and ploughing marks as a result of wear with running hours. Atomic Absorption Spectroscopy (AAS) was used to measure Fe concentration level in the grease of different run hours. AAS concentration of 5.350 mg/L was observed at 1000 h of running which was only 0.432 mg/L at 50 running hours. These investigations offer a better correlation between spectroscopic and vibration variables and can be used to assess the wear in bearing surfaces effectively.