Submicro- and nanometer-sized glass double-barrel pipets have been fabricated by a laser puller with new pulling programs and have been used to support submicro- and nanometer dual liquid/liquid interfaces. The smallest pipet that can be made by this approach is approximately 20 nm in radius. These pipets have been characterized by cyclic voltammetry and scanning electron microscopy. Generation/collection mode of charge-transfer reaction is demonstrated at the submicro- and nanometer dual-liquid/liquid interfaces. The dependence of collection efficiency upon geometric parameters of the pipets has been discussed. Among the micro-, submicro-, and nanopipets, we have found that the submicro-double-barrel pipets have higher collection efficiencies than that of others and are also very close to the values predicted by the theory. Therefore, in terms of G/C mode applications, the optimal size of double-barrel pipets should be in submicrometer scale. As one of the examples of special application, we have also demonstrated that in the case of no supporting electrolyte, only the nanometer double-barrel pipets can provide reasonably good G/C results.