Cyclic voltammetry, impedance and chronocoulometry have been employed for quantitative study of adenosine (Ado) adsorption at the bismuth single crystal plane\0.05 M Na2SO4 aqueous solution interface. The adsorption of Ado on Bi planes reveals the existence of two capacity pits resulting in reversible, mainly physical adsorption at zero charge potential E-sigma = 0, and more stronger interaction at moderate positive charge densities. The adsorption isotherms, Gibbs adsorption energy Delta G(ads)(0), the limiting Gibbs adsorption Gamma(max), and other adsorption parameters have been determined. At potentials close to E-sigma = 0, the value of Gamma(max) and the absolute value of Delta G(ads)(0) of Ado increase from Bi(111) to Bi(001). The very low values of Gamma(max) and the limiting potential shift of zero charge E-N approximate to 0 caused by the replacement of the water monolayer by the monolayer of Ado, have beeen explained by the flat orientation of Ado molecules at Bi(lll). The adsorbed Ado molecules at the Bi(001) plane have probably a tilted orientation, but with the value of E-N approximate to 0, i.e. the total dipole moment <(mu)over bar> approximate to 0. The molecular interaction parameter a in the Frumkin isotherm has a negative value and its negative decreases from Bi(001) to Bi(lll) as the reticular density of planes increases.