有机硫化合物指含有硫元素的有机化合物，有机硫化学即是研究有机硫化合物的有机化学分支。有机硫化合物广泛存在于自然界中，具有特征性的令人讨厌的气味，但少数也带甜味。很多化石燃料，如煤、天然气、石油中，都含有一定数量的有机硫化合物，燃烧时会释放出有毒的二氧化硫气体。为避免污染，脱硫已成为石油炼制中很重要的一个环节。

按质量计，人体中硫元素占0.25%， 绝大多数以有机硫化合物的形式存在。20种常见氨基酸中，也有两种含有硫元素，分别是半胱氨酸和甲硫氨酸。

硫属于氧族元素，硫和氧具有相似的价电子层结构，有机硫化合物在某些程度上与有机含氧化合物有些相似，例如它们都可生成醇／硫醇、醚／硫醚等。但和氧原子相比，硫是第三周期元素，原子半径较大，电负性较小，且3d轨道也可以成键。因此，硫原子还可以形成一系列常见的四价及六价有机硫化合物，如亚砜、砜、亚磺酸和磺酸。它们都不存在对应的含氧化合物。

Organosulfur compounds are organic compounds that contain sulfur. They are often associated with foul odors, but many of the sweetest compounds known are organosulfur derivatives, e.g., saccharin. Nature abounds with organosulfur compounds—sulfur is essential for life. Of the 20 common amino acids, two (cysteine and methionine) are organosulfur compounds, and the antibiotics penicillin (pictured below) and sulfa drugs both contain sulfur. While sulfur-containing antibiotics save many lives, sulfur mustard is a deadly chemical warfare agent. Fossil fuels, coal, petroleum, and natural gas, which are derived from ancient organisms, necessarily contain organosulfur compounds, the removal of which is a major focus of oil refineries.