Electrochemical intercalation of Na in solid C-60 has been performed using polymer electrolytes and very slow rate stepwise voltamperometry. Five reduction steps are observed as on the LixC60 system we studied previously, but with appearance of solubility of the compound beyond the first one. That paper focus on that first step which presents the same hysteresis and X-rays diffraction pattern as in LixC60 where it was shown to correspond to Li0.5C60 formation. The fact that the polymer electrolyte could play a role is discussed.