The fragmentation of a number of organomercury compounds under electron impact has been examined. In the symmetrical diarylmercury compounds it seems that the first fragmentation is loss of aryl radical to form arylmercury cation which then loses mercury to give aryl cation. Another important fragmentation is the extrusion of mercury from the parent ion to give a biaryl-type system. Fragmentation of the substituted aromatic compounds before C–Hg bond fission is also observed. In dialkylmercury compounds the dominant path is fission of the C–Hg bond even when an alternative path leading to a very stable cation (C₇H₇⁺) is available.

In the α-halogenomercurated carbonyl compounds examined the dominant structural feature determining the direction of fragmentation is the carbonyl group, e.g. in α-chloromercuryacetone α fission leads to acetyl and α-chloromercuryacetyl ions of similar intensity. Di-(α-ethoxycarbonylbenzyl)mercury shows only Hg⁺ and mercury-free organic ions formed by extrusion of mercury and subsequent fragmentation of the extrusion product.

When pairs of symmetrical diaryl and dialkyl mercury compounds were introduced into the mass spectrometer, ions of the type R¹–Hg–R² have been observed to accompany R₂¹Hg and R₂²Hg. This exchange was confirmed by the appearance of mixed extrusion products R¹–R².