In the present work the possibility of pure hydrogen production by a solid oxide electrochemical reformer (SOER) is examined. Initial reagents are water steam, flowing into the cathode channel and octane flowing into the anode channel. Three modes of reforming are considered: (i) steam reforming (SR-mode), (ii) preliminary octane partial oxidation (PO-mode) and (iii) preliminary octane reforming by exhaust anode gas recycling (EAGR-mode). A parametric analysis is carried out that can be easily applied for various hydrocarbons. It was found that the electromotive force (EMF) value depends mainly on the ratio of steam moles' number supplied to the cathode space to the number of hydrogen output moles (k-parameter). It was also found that EMF increases with k increase, while is weakly affected from the temperature and the heat losses amount. Moreover, the EMF average value under the PO-mode is lower than that under the SR-mode. Finally, it is shown that the SOER optimum characteristics can be reached under the EAGR-mode, since it provides the most favorable combination of the reforming efficiency and the rate of the electrochemical process.