Supported　liquid-phase　catalysts　(SLPCs)　combine　the　advantages　of　homogenous　liquid-phase　catalysts　and　heterogeneous　catalysis　(e.g.,　controllability　of　active　centers　and　efficient　product–catalyst　separation).　Generally,　SLPCs　manifest　as　a　liquid-phase　catalyst　film　or　droplet　adsorbed　onto　the　surface　of　a　porous　support,　such　as　ionic　liquid-phase　catalysts.　Here,　we　extend　this　idea　and　develop　a　solvent-free　liquid-phase　catalyst　supported　on　hollow　spheres.　We　report　sandwich-like　B2O3@BPO4　hollow　spheres　synthesized　through　a　one-step　template-free　method.　At　reaction　temperatures　(>450　°C),　melted　B2O3　supported　on　the　surface　of　BPO4　hollow　spheres　acts　as　a　catalytically　active　species　for　the　selective　oxidative　dehydrogenation　of　propane　to　propene,　with　an　excellent　productivity　of　0.79　gC3H6　gcat−1　h−1　and　a　high　stability　at　550　°C.　We　also　found　a　phenomenon　of　tertiary　aggregation　during　the　formation　of　this　sandwich-like　hollow　sphere.　Additionally,　the　kinetic　experiments　indicate　oxygen　activation　on　the　B2O3@BPO4　surface　and　second-order　rate　dependence　with　respect　to　the　partial　pressure　of　propane.　This　work　may　open　a　new　avenue　for　the　design　and　construction　of　metal-free　oxides　used　as　high-temperature　SLPCs.　©　2019　Elsevier　Inc.