In a jet-type singlet oxygen generator, we have studied the generation of O
2(
1Δ) via the reaction of chlorine gas with aqueous basic hydrogen peroxide (BHP) and with basic deuterium peroxide (BDP). The O
2(
1Δ) detachment yield with BDP is measured to be 72.5
1.5%, merely 2.5% higher than that with BHP, despite a 10 times longer O
2(
1Δ) lifetime in BDP than in BHP. By a careful kinetic analysis of the Cl
2 + BHP(BDP) reactions, we found that the main resistance that prevents the nascent O
2(
1Δ) from escaping off the solution into the bulk gas flow does not lie in the liquid or gas phase, but in the gas/liquid interface. Thus, the seemingly weird experimental result can be justified by postulating a higher energy barrier at the O
2(
1Δ)/BDP interface than that of the O
2(
1Δ)/BHP so as to detain the O
2(
1Δ) for a longer time in BDP. In fact, this postulation has been proved as follows: according to the physical model of Copeland and Zagidullin, the O
2(
1Δ) mass accommodation coefficient is calculated from our experimental solvation detachment yield to be ~4.0 × 10
−6 on the BHP surface and ~1.7 × 10
−6 on the BDP surface. Then, based on the thermodynamics of phase equilibrium in dilute solutions, the corresponding Gibbs energy of O
2(
1Δ) at the BHP surface is computed as ~2.65 × 10
4 J/mol, and the value of O
2(
1Δ) at the BDP surface is ~2.86 × 10
4 J/mol. This higher O
2(
1Δ)/BDP interface energy barrier may result from both larger D
2O molecular mass and stronger hydrogen bonding between D
2O molecules in BDP solution. The present methodology can be further improved by using microwave-discharge production of O
2(
1Δ) so as to make direct measurements of its quenching probability. Hence, more key thermodynamic and kinetic information about the O
2/aqueous electrolyte solution interfaces will be made available. Work along this line is now under way.