Reagent bottles, also known as media bottles or graduated bottles, are containers consisting of glass, plastic, borosilicate, or a similar material and capped with appropriate caps or stoppers. They are designed to hold chemicals in liquid or powder form for laboratory use and are stored in cabinets or shelves. Some reagent bottles are tinted amber (actinic), brown, or red to protect light-sensitive chemical compounds from visible light, ultraviolet, and infrared radiation, which may alter them; other bottles are tinted blue (cobalt glass) or uranium green for decorative purposes.

The bottles are called "graduated" because they include markers on the sides that indicate the approximate (sometimes with a 10% inaccuracy) amount of liquid at a specific level within the container. Reagent bottles are a form of laboratory glassware. The term "reagent" refers to a material that is a component of a chemical reaction (or an ingredient of which), whereas "media" is the plural version of "medium," which refers to the liquid or gas in which a reaction occurs, or is a processing chemical instrument such as a flux.

Bottle sizes include 100 mL, 250 mL, 500 mL, and 1000 mL (1 liter). Older bottles, particularly for medical usage and costly substances, can be found with volumes much below 100 mL.

The caps and stoppers used to shut reagent bottles are just as essential as the bottles themselves, and the choice of which cap to use is determined by the substance stored in the container and the amount of heat that the cap can withstand. Reagent bottle caps are usually referred to be "autoclavable".