Display omitted A selenoantimonate (C4H14N2)0.5Cu2SbSe3 (1) (C4H12N2 = 1, 4-butanediamine) was synthesized by solvothermal synthesis using 1, 4-butanediamine as solvent. By single-crystal X-ray diffraction, compound 1 has a two-dimensional (2-D) layered structure composed of a protonated organic amine (C4H14N2)0.5+ and an anionic layer Cu2SbSe3- containing the 6-membered rings (6-MR) Cu2SbSe3 and the 10-membered rings (10-MR) Cu3Sb2Se5. Solid-state UV-diffuse reflectance analysis showed that 1 has a band gap value of 1.85 eV, indicating its potential semiconducting properties. This paper studied the photodegradation properties of selenoantimonate containing the transition metal Cu for the first time, and found that its degradation rate methylene blue (MB) was 68.5 %. In addition, a series of characterizations were also performed.