A　novel　complex,　[Co0.5Ni0.5(C6H12N4)2(H2O)4]2[Co0.5Ni0.5(H2O)6]2[SO4]4·13H2O,　has　been　prepared　and　its　hexagonal　crystal　was　obtained　from　aqueous　solution　by　solvent　evaporation　method.　Single　crystal　X-ray　diffraction　revealed　that　the　complex　crystallizes　in　triclinic　system,　space　group　P−1　with　lattice　parameters　a　=　9.2268(7)　Å,　b　=　13.3529(9)　Å,　c　=　15.9211(11)　Å　and　interfacial　angles　α　=　66.246(3)°,　β　=　89.193(3)°,　γ　=　89.303(3)°.　The　coordination　geometry　around　the　metal　ion　is　described　as　distorted　octahedron　in　which　the　two　hexamethylenetetramine　molecules　occupy　two　apical　sites.　TGA　revealed　three　main　mass　loss　steps　at　about　71 °C,　219　and　475 °C,　which　represents　the　temperature　of　dehydration,　skeleton　decomposition　and　sulfate　decomposition,　respectively.　Further,　the　UV-VIS　spectra　showed　an　intense　transmission　around　293 nm　and　strong　absorption　in　visible　region,　indicating　the　application　potential　as　ultraviolet　light　filters　(ULFs).　Variable-temperature　magnetic　measurements　were　carried　out　for　the　complex,　which　was　found　to　obey　the　Curie-Weiss　law　with　Cm　=　8.475　cm3 K mol−1,　θ　=　− 1.140 K.　Graphical　Abstract:　A　new　complex,　[Co0.5Ni0.5(C6H12N4)2(H2O)4]2[Co0.5Ni0.5(H2O)6]2[SO4]4·13H2O,　has　been　introduced　for　its　good　optical　feature　of　high　transmission　under　350　nm　and　strong　absorption　in　visible　region.[Figure　not　available:　see　fulltext.]　©　2022,　The　Author(s),　under　exclusive　licence　to　Springer　Science+Business　Media,　LLC,　part　of　Springer　Nature.