Nucleosides and Nucleotides are polydentate ligands, offering potential binding sites for metal ions. Energy interaction parameters: Slater Condon F_k (cm^-1), Spin Orbit interaction ξ_4f  (cm^-1), Nephelauxetic Ratio (β), Bonding (b1/2) and Covalency (δ) parameter for the interaction of Pr(III) with Nucleoside and Nucleotide are evaluated to study the mode of binding of the Nucleic Acid Components (Guanosine and Guanosine Triphosphate) with Pr(III). Further Intensity Parameters like Oscillation Strength and Judd Ofelt Parameter (T2, T4, T6) have been evaluated to investigate degree of inner or outer sphere co-ordination of Pr(III) with Nucliec Acid ligands. Comperative Absorption Spectra in different solvents substantiate the informations, gathered from the evaluated values of both energy interaction and intensity parameters. Further evaluation of Thermodynamic parameters (ΔG, ΔH and ΔS) through Kinetic studies enable to provide the detailed information about the reaction pathways and thermodynamic behavour of the complexation process of neucleosides and nucleotides with Pr(III) and Ca²⁺.