Salts of this compound, e.g. disodium methyl arsonate, have been widely used in as herbicides and fungicides in growing cotton and rice.

[2] Near physiological pH, methanearsonic acid converts to its conjugate bases, the methylarsonates.

This historically significant conversion is called the Meyer reaction:[3] The then-novel aspect of the reaction was that alkylation occurs at arsenic, leading to oxidation of arsenic from oxidation state +3 to +5.

The biomethylation of arsenic compounds is thought to start with the formation of methanearsonates.

The methanearsonates are the precursors to cacodylates, again by the cycle of reduction (to methylarsonous acid) followed by a second methylation.