Acid-base neutralisation reactions between nitrogen bases, tertiary bases and antimony(V), antimony (III), arsenic(III), iron (III), tin (IV), tellurium (IV) and titanium(IV) chlorides and fluorosulphuric and sulphuric acids in nitromfthane have been studied conductometrically, and explamed on the basis of the autoionisation of nitromethane as: 2CH3NO2 \(\rightleftharpoons\) CH3NO2H++CH2NO2 -. This process of neutralisation has been confirmed by isolation of products which have been found to contain molecules of nitromethane.