Shape control is an important technique for improving the quality and activity of nanomaterials. Two types of one-dimensional manganese dioxide (MnO2) nanocrystals with different shapes were synthesized by facile hydrothermal methods as the catalyst materials for both sensor fabrication and heterogeneous catalytic reactions. The nanomaterials present an alpha-crystalline phase (alpha-MnO2) in either nanotube or nanowire shapes. The alpha-MnO2 nanocrystals were found to have a favorable electrochemical property that can be used to fabricate sensors for rapid detection of hydrogen peroxide and L-ascorbic acid. The alpha-MnO2 also functioned well as a catalyst for the oxidation of phenol and chlorophenol by peroxymonosulfate and hydrogen peroxide in an aqueous solution at room temperature. Comparison between the two differently shaped alpha-MnO2 catalysts indicated that nanowires performed better than nanotubes in both electrocatalytic detection and catalytic phenol degradation. Compared to alpha-MnO2 nanotubes, nanowires have a much greater surface area and lower negative surface charge density, which are probably the main reasons for their higher catalytic activities. (C) 2016 Elsevier B.V. All rights reserved.