Methoxide is an organic salt, in pure form a white powder.

In Organic chemistry, the methoxide ion has a formula of CH3O- and is the conjugate base of methyl alcohol.

In biodiesel production, methoxide is a product of mixing methanol and sodium hydroxide, yielding a solution of sodium methoxide (NaO-CH₃) in methanol and a significant amount of heat.

Sodium methoxide in methanol is a liquid that kills human nerve cells before any pain can be felt. In the event of contact with methoxide, rinse the contacted area with water, seek medical attention immediately.

Methoxide is also highly explosive.

Making sodium methoxide is the most dangerous step in making biodiesel. For this reason, the safety of the design of your equipment and workspace should be carefully considered before use, and protective clothing and a respirator should be worn during handling. Only as much as is intended to be use immediately should be created.