The electrochemical oxidation of 1,2,3,4-tetra-tert-butyl-1,2,3,4-tetramethylcyclotetrasilane [t-Bu(Me)Si](4) (I) and hexamesitylcyclotrisilane (Mes(2)Si)(3) (II) in CH2Cl2-CH3CN (4:1 v/v) solutions containing a different electrolyte, under air or argon atmospheres, has been studied. The effects of electrolyte, applied potential and electrode material were investigated. The anodic oxidation of I led to oxygen insertion and gave cyclic siloxanes as the major products. Under specific conditions, in the presence of tetraethylammonium perchlorate or tetrabutylammonium hydrogen sulfate, and under argon atmosphere, the sole product obtained was cyclic siloxane [t-Bu(Me)Si](4)O in 94% and quantitative yield, respectively. The electrochemical oxidation of II, unlike that of I, involves ring opening followed by Si-Si bond cleavage and a further reaction with the electrolyte to generate (mostly) linear products of type : X-(Mes(2)Si)(n)-Y (n = 1, 2; X, Y = mesityl, H, OH or F).