<p>We present novel X-ray absorption spectroscopy (XAS) results on Mn-doped CeO₂ that are capable of providing insights into local structural parameters such as oxidation states, defect structure and defect chemistry revealing important information on the modifications at atomic level upon doping Mn into CeO₂ host.. For this, Mn doped (0-20 at%) ceria nanoparticles (CeO₂NPs) were successfully prepared using chemical precipitation method and their properties were compared with those of pure CeO₂ NPs. Mn doping produced lattice defects such as oxygen vacancies as confirmed from X-ray absorption near edge spectroscopy. NP formation in pure CeO₂ resulted in modification in bond distances and slight reduction in the Ce-O coordination number compared to bulk CeO₂, which is further modified employing Mn doping. The coordination number decreased down to 4.7 in 20 at% Mn:CeO₂ NP as compared to 8 in standard bulk form as confirmed from EXAFS analysis. XAS analysis of the samples showed a mixture of 3+ and 4+ oxidation state of CeO₂ in both bulk as well as nano forms. Due to increase in oxygen vacancies upon doping there is slight lattice distortion as also confirmed, from Raman studies. The Raman measurements showed a shift in F_2g vibrational band position from 466 cm^-1in bulk to 445 cm^-1in Mn doped NPs along with a broadening of this most intense Raman peak. This was followed by the appearance of an additional peak at ~600-650 cm^-1 resulting from oxygen defects. The ratio of these peaks revealed ~18% oxygen vacancies incorporation at 15% Mn doping. The observed results are correlated and explained on the basis of an increase in atomic disorder along with the presence of oxygen vacancies after doping of Mn into CeO₂. This study is useful in understanding the structural, vibrational and optical properties of this material.</p>