AbstractThe dielectric properties of four 4‐n‐alkyloxyphenyl 4‐n‐alkyloxybenzoates with nematic, smectic C and partly additional SAphases were investigated. In 2 substances for ϵ′ reproducible values also in the smectic phases resulted allowing to conclude on a good orientation in the samples. In all 4 substances the dielectric relaxation in the MHz region was measured and the respective activation energies were determined. The molecular mobility in the SCphases is higher than in the SAphases, however comparable with that of the nematic phases. In all 3 phase types a single relaxation mechanism exists, which is explained as rotation of the molecules around a