一氯化硒是一种无机化合物，化学式为Se₂Cl₂。

一氯化硒可以由硒的氯化得到。硒和氯气的化合反应可以直接发生，也可以用氯处理硒的二硫化碳悬浮液得到。

2 Se + Cl₂ → Se₂Cl₂

也可以利用硒、二氧化硒和盐酸的反应制备一氯化硒：

3 Se + SeO₂ + 4 HCl → 2 Se₂Cl₂ + H₂O

Selenium monochloride is an inorganic compound with the formula Se₂Cl₂. Although it is called selenium monochloride, a more descriptive name might be diselenium dichloride. It is a reddish-brown, oily liquid that hydrolyses slowly. It exists in chemical equilibrium with SeCl₂, SeCl₄, chlorine, and elemental selenium. Selenium monochloride is mainly used as a reagent for the synthesis of Se-containing compounds.