The reduction at a mercury electrode in dimethylformamide of five variously substituted indenes bearing at least one (acidic) hydrogen at C(1) was carried out, under self-protonation conditions and in the presence of phenol as a proton donor. Reduction occurred exclusively at the C(2)–C(3) double bond of the five-membered ring and afforded the corresponding indans of various configurations, with a marked predominance of the cis isomer, under kinetic control. The stoicheiometry was in agreement with a two-electron, two-proton reduction process involving all indene in the case of the presence of phenol or 1/3 indene under self-protonation conditions, the remaining 2/3 acting as a proton donor. Under both conditions direct protonation of the radical anion rather than the dianion formed by disproportionation was observed. Voltammetric and kinetic behaviour of the indenes was found to be dependent on the structure of the substrates, with differences in rate constants of 3–4 orders of magnitude; the balance between the acidity of the indene and the basicity of the corresponding radical anions was discussed. The stereochemistry observed was rationalised in terms of steric effects on the direction(s) of protonation of the intermediates.