The X-ray crystal structure and electrical conductivity properties of a 1:1 BEDT-TTF salt containing (AuBr 2Cl 2) - are reported. The unit cell consists of square-planar gold (III) anions segregated by stacks of BEDT-TTF + cations with a repeat pattern of 4.467(2) Å along the crystallographic a axis. Four-probe variable-temperature conductivity measurements indicate that this material is a semiconductor with an activation energy of 0.13 eV. ESR measurements carried out on an oriented single-crystal specimen show a monotonic decrease in linewidth from 19 to 2.1 G over the temperature range 300-100 K.