The deprotonation constants of uridine (K1andK2), thymidine (K1andK2), cytidine (K1andK2), guanosine (K1,K2, andK3), and xanthosine (K1,K2, andK3) have been obtained in water from EMF measurements of Harned-Ehler type cells comprising H2and Ag-AgI electrodes at different temperatures. The pKvalues were substituted in the temperature equation: pK = AT−1 + B + CTandA,B, andCwere obtained by the method of least squares. Related thermodynamic quantities viz. ΔG0,TΔS0, and ΔH0were obtained from coefficientsA,B, andCof the respective nucleosides.Keywords: deprotonation energetics, uridine, thymidine, cytidine, guanosine, xanthosine.