As degradable biomaterials, the higher degradation rate in a physiological environment is the main challenge for the application of magnesium alloys. For this reason, the effect of the rapid solidification processing (RSP) on the corrosion resistance of Mg-13Li-3Al-1Zn-0.5Sr-0.5Ca (Mg-13Li-X) was studied using electrochemical techniques at the corrosion potential (E-corr). The alloy with a chemical composition of Mg-13Li-X was prepared, melted and cast in a low carbon steel crucible under a protective gas of Ar, then melted two to four times to ensure compositional homogeneity. Rods with diameters of 1, 3 and 6 mm were prepared by a rapid solidification process. Uniform corrosion rates were measured at 37 +/- 0.5 degrees C, which is equal to the normal human body temperature, in a pH 7.2-7.4 Hank's balanced salt solution (HBSS) adjusted by HCl and NaOH using electrochemical impedance spectroscopy. The surface morphologies of experimental samples before and after the corrosion in Hank's solution were characterised by scanning electron microscopy (SEM) observation complemented by energy disperse spectrometer (EDS) analysis. The results show that the corrosion behaviours of the magnesium-lithium alloys are significantly influenced by the rapid solidification process. The RSP treated samples led to higher impedance and polarisation values than conventional Mg-13Li-X alloy and AZ31 and AZ91. The minimum corrosion current density of O6 species was 13.92 mu A cm(-2). And the corrosion potential (E-corr) was -0.326 V, moved about 1 V towards noble compared to AZ31 (-1.46 V), AZ91 (-1.36 V) and JDBM (-1.79 V). The results indicated that RSP could increase their polarisation resistance and reduce the corrosion current densities, increase the corrosion resistance and promote the surface passivation in turn. The results suggest that the novel RSP Mg-13Li-X alloy can be considered for in-depth research in vitro corrosion environment.