A　unique　Rh/TiO2　solid　acid　catalyst　modified　with　H2SO4　was　synthesized　and　evaluated　in　the　esterification　reaction　of　propylene　glycol　methyl　ether　and　decomposition　of　methyl　orange　(MO)　in　aqueous　phase　under　halogen　lamp　irradiation.　For　this　purpose,　rhodium　(Rh)　nanoparticles　were　loaded　on　SO42 −/TiO2　via　the　photo-deposition　method.　It　was　found　that　SO42 −/Rh–TiO2　exhibited　stronger　catalytic　activity　than　SO42 −/TiO2.　The　new　catalysts　were　characterized　by　X-ray　powder　diffraction　(XRD),　Brunauer–Emmett–Teller　(BET),　Transmission　electron　microscopy　(TEM)　and　high-resolution　(HRTEM),　X-ray　photoelectron　spectroscopy　(XPS)　and　Fourier　Transform　infrared　spectroscopy　(FTIR).　Results　from　XRD　and　BET　show　that　SO42 −/Rh–TiO2　has　higher　specific　surface　area　and　smaller　pore　size　than　SO42 −/TiO2.　The　distribution　of　loaded　Rh　was　found　to　be　uniform　with　a　particle　size　of　2–4 nm.　Data　from　XPS　reveal　that　Rh　primarily　exists　as　Rh0　and　Rh3 +　in　Rh–TiO2　and　SO42 −/Rh–TiO2.　These　valence　forms　of　Rh　likely　contribute　to　the　enhanced　catalytic　activity.　Furthermore,　FT-IR　spectra　of　the　catalysts　show　an　abundance　of　surface　hydroxyl　groups,　which　help　the　formation　of　hydroxyl　radicals　and　the　enhancement　of　surface　acid　density.　The　results　show　that　more　acid　sites　are　formed　on　the　sulfated　Rh–TiO2,　and　these　acidic　sites　are　largely　responsible　for　improving　the　catalytic　performance.　This　superior　SO42 −/Rh–TiO2　catalyst　has　potential　applications　in　reactions　requiring　efficient　acid　catalysts,　including　esterification　reactions　and　waste　water　treatment.　©　2016　Elsevier　B.V.