The electrochemical hydrogen storage of multi-walled carbon nanotubes (MWNTs) has been investigated. The MWNTs were synthesized by chemical vapor deposition using a lanthanum nickel alloy as catalyst in a C2H2/H2 atmosphere. The purified MWNTs have a high hydrogen storage capacity of 380 mAh/g under a condition of 200 mA/g charging current density and 100 mA/g discharging current density. The discharging curve has an approximate voltage plateau of 0.8 V. The discharging capacity is increased as the number of cycles rises from 1 to 41. These curves showed a good and stable charging/discharging performance of CNTs. We have also investigated the effect of the weight ratio of carbon nanotubes (CNTs) to Ni on the discharging capacity of CNTs-Ni electrodes, and found that the optimum ratio is 1:9 in our experimental range. Furthermore, the polarization behavior of CNTs was studied, which exhibited that CNTs using lanthanum nickel alloy as catalyst have better electrochemical activation.