Hybrid supercapacitors with the composite electrode materials display high energy density at the expense of the reduced cycle stability. Herein, we provide new data on the electrochemical performance of hybrid electrodes based on mixed nickel hydroxides/manganese oxides in the form of structured and multiphase composites. As structured composites, two types of less known structure modifications are examined: interstratified modification of Ni(OH)(2) (i.e. alpha/beta(IS)-Ni(OH)(2)) and e-modification of MnO2. The multiphase hydroxide/oxide composites are prepared by the conventional grinding of alpha/beta(IS)-Ni(OH)(2) and epsilon-MnO2 and by the in-situ formation after the reaction of layered Na0.5Ni0.5Mn0.5O2 with mixed LiOH-KOH electrolyte. The structure, morphology and porous texture properties of composites are analyzed by means of powder X-ray diffraction, scanning electron microscopy (SEM) and low-temperature nitrogen adsorption, respectively. The electrochemical performance of composites electrodes is determined by galvanostatic experiments in concentrated individual KOH and mixed LiOH-KOH electrolytes. The ex-situ X-ray diffraction is used to monitor the changes in composite electrodes during electrochemical cell function. It has been found that alpha/beta(IS)-Ni(OH)(2) participates in electrochemical reaction concomitantly with H2O and Li+ intercalation, while the electrochemical performance of epsilon-MnO2 is determined by surface adsorption of electrolyte alkaline ions. The best electrochemical performance (in terms of discharge capacity, rate capability and cycling stability) is achieved for alpha/beta(IS)-Ni(OH)(2) especially when it works in mixed LiOH-KOH electrolyte. In alkaline electrolyte solution, layered Na0.5Ni0.5Mn0.5O2 is transformed into a phase mixture between slightly sodium deficient oxide Na0.5-xNi0.5Mn0.5O2 and alpha-type nickel hydroxide. Thus generated multiphase composite demonstrates the highest areal capacitance and a rate capability comparable with that for alpha/beta(IS)-Ni(OH)(2). (C) 2018 Elsevier Ltd. All rights reserved.