The　NiO　samples　(NiO-HMTA,　NiO-HMTA-PEG,　NiO-HMTA-PVP,　and　NiO-urea,　respectively)　with　a　surface　area　of　31-66　m(2)/g　and　porous　nanoflower-　and　nanourchin-like　morphologies　were　prepared　via　the　hydrothermal　route　with　hexamethylenetetramine　(HMTA)　or　urea　as　precipitator　in　the　absence　or　presence　of　surfactant　(poly(ethylene　glycol)　(PEG)　or　polyvinyl　pyrrolidone　(PVP)).　It　is　shown　that　NiO-HMTA-PVP　possessed　the　highest　surface　area　and　O-ads　concentration　and　the　best　reducibility.　The　NiO-HMTA-PVP　catalyst　performed　the　best　(T-50%　=　253　degrees　C　and　T-90%　=　266　degrees　C).　The　excellent　catalytic　activity　of　NiO-HMTA-PVP　was　associated　with　its　large　surface　area,　high　Oads　concentration,　and　good　reducibility.　(C)　2012　Elsevier　B.V.　All　rights　reserved.