Compounds　[Ln(HPO3)[S0.5(OH)4]　(Ln　=　La,　Ce)　and　La[HPO2(OH)]SO4·H2O　represent　the　first　reported　examples　of　sulfophosphite　materials　constructed　through　the　co-assembly　of　HPO3　and　SO4　building　units.　The　structures　of　Ln(HPO3)[S0.5(OH)4]　(Ln　=　La,　Ce)　feature　2D　anionic　Ln–P–O　layers,　composed　of　1D　Ln–O　chains　bridged　by　HPO3　units,　which　are　further　linked　by　S(OH)4　tetrahedra　to　form　its　3D　framework.　La[HPO2(OH)]SO4·H2O　consists　of　1D　La–S–O　chains　formed　by　La2O14　dimers　and　SO4　tetrahedra,　which　are　further　extended　into　a　three-dimensional　network　via　HPO2(OH)　linkers.　The　partial　occupancy　of　sulfur　sites　in　Ln(HPO3)[S0.5(OH)4]　(Ln　=　La,　Ce)　was　validated　by　energy-dispersive　X-ray　spectroscopy　and　X-ray　photoelectron　spectroscopy.　Optical　properties　investigated　through　diffuse　reflectance　spectroscopy,　combined　with　Urbach　tail　fitting　and　Tauc　plot　analysis,　revealed　that　all　three　compounds　exhibit　direct　band　gaps　of　4.53,　4.55,　and　4.49　eV,　respectively.　This　work　not　only　broadens　the　structural　and　compositional　diversity　of　phosphite-based　materials　but　also　provides　a　novel　design　strategy　for　the　development　of　functional　sulfophosphites　with　tunable　properties.　©　2025　Elsevier　Inc.