Synthesis of electrode materials with desirable morphology and size for supercapacitor applications is an important and challenging research topic. In this work, a series of NiCo2O4 nanostructures with different morphologies on nickel foam are obtained through a facile hydrothermal method. The important role of NH4F in formation of these nanostructures has also been investigated based on the NH4F-independent experiments. When evaluated as supercapacitor electrodes, the NiCo2O4 electrode (using 6 mmol NH4F) exhibits the optimal electrochemical performance, which might hold some potential for supercapacitor applications. Such excellent performance is attributed to the ultrathin and mesoporous structure of the interconnected NiCo2O4 nanosheets, and directly grown on nickel foam with robust adhesion. The electrochemical results show that different morphologies could lead to different electrochemical properties. This work could provide a deeper understanding of the morphology effect on the supercapacitive performance. This work also suggests the importance of rational design and synthesis of electrode materials with desirable morphology and size for high performance supercapacitor applications. (C) 2014 Elsevier Ltd. All rights reserved.