KCuZrSe~3 has been synthesized by the reactive flux method and structurally characterized by single-crystal X-ray diffraction. The crystal data: KCuZrSe~3, orthorhombic, Cmcm, Z=4, a=0.3883(7)nm, b=1. 4447(2)nm, c=1.0186(3)nm。V=0.5715(2)nm^3, Dc=5006mg.nm^-^3, Mr=430.74, F(000)=760, μ=25.217mm^-^1, λ (MoKα)=0.07107nm。R[R^2>2σ(F^2)]=0. 0471. The crystal is bult by [CuZrSe~3]^- layers separated by K^+ cations. In the [CuZrSe~3]^- layer, Zr^4^+ and Cu^+ are respectively eight-four-coordinated to Se^2^-. K^+ cations are coordinated by eight Se^2^- in an antitetragonal prismitic arrangment. The crystal is a thermodynamically stable phase. It is possible to synthesize the thermodynamically stable phase by reative flux reaction at intermetiate temperature.

Key words: SELENIUM COMPOUNDS, ZIRCONIUM COMPOUNDS, COPPER COMPOUNDS, POTASSIUM COMPOUNDS, SOLIDPHASE SYNTHESIS, CRYSTAL STRUCTURE