The compounds R2BiO2CR′ (R = Ph, p-MeC6H4, p-MeOC6H4, p-EtOC6H4 or C6F5; R′ = Me or CF3) and RBi(O2CR′)2 (R = Me, Ph, p-MeC6H4, p-MeOC6H- or p-EtOC6H4; R′ = Me or CF3) are formed on acidolysis of the corresponding triarylbismuthines in ether. The products were readily identified by 1H n.m.r. spectroscopy, even in complex mixtures, because of the successive downfield shifts of the aromatic resonances as the number of aryl groups decreases. By contrast with triarylbismuth compounds, R3 -nBi(O2CR′), (R = aryl; n = 1 or 2) complexes are readily hydrolysed, whereas MeBi(O2CMe)2 is oxygen-sensitive but more stable to hydrolysis. The compounds undergo aryl redistribution reactions in dimethyl sulfoxide.