The cubic liquid crystalline (I-1) phase formed by sodium octanoate, n-octane, and water (40.0:4.0:56.0% by weight) was studied by means of a fluorescence quenching (FQ) technique. Time resolved fluorescence was measured for small amounts of solubilized pyrene (P), both with and without a solubilized quencher (Q), dimethylbensophenone. The FQ data show that the Q and P molecules are captured in closed amphiphilic aggregates consisting of ca. 75 sodium octanoate molecules at 298 K. From these results together with already published X-ray data the number of micelles per unit cell was estimated to be eight. NMR self-diffusion studies of the surfactant and the hydrocarbon were carried out on the above mentioned cubic phase as well as on the corresponding phases formed with p-xylene and cyclohexane. These experiments convey information on the lifetime of the surfactant and the hydrocarbon in the aggregates and also on the structure of the cubic phase.