A gas washing bottle is a laboratory glass bottle used to purify gases by washing them with a liquid. The bottle has a sidearm or a tube on the side for the introduction of the gas, and a bottom outlet for the purified gas to exit. The gas is passed through the liquid, which removes impurities and contaminants before the purified gas is released.

Gas washing bottles are commonly used in chemistry and physics experiments, especially when a pure gas is required. The bottle can be made of clear or amber glass to protect the contents from light and is available in various sizes and capacities. The type of liquid used for gas washing depends on the gas being purified and the impurities to be removed.