The　self-assembly　of　the　cationic　surfactant　cetylpyridiniumchloride　(CPC)　in　cyclohexane　was　studied　using　polarizing-microscopy　(POM),　small　angle　X-ray　scattering　(SAXS),　and　rheology　measurements.　Homogeneous　solutions　of　CPC/aromatic　salts　were　produced　using　aromatic　salts,　specifically,　NaBzs,　NaNphs,　or　NaSal.　The　majority　of　the　samples　showed　highly　viscous　gel-like　appearances.　SAXS　measurements　together　with　POM　observations　indicate　hexagonal　liquid　crystals　in　both　the　CPC/NaNphs　and　CPC/NaSal,　while　multiple　types　of　aggregates　were　shown　to　co-exist　in　the　CPC/NaBzs.　These　were　attributed　to　the　interactions　of　aromatic　counterions　with　the　pyridinium　head-group　of　CPC,　resulting　in　increased　size　of　the　CPC　head　to　different　extents　depending　on　the　aromatic　counterions.　The　formation　of　core-shell　aggregates　consequently　caused　further　packing　into　liquid　crystals.　The　specific　role　of　NaSal　that　carried　an　ortho-hydroxyl　in　its　benzene　ring　is　discussed,　and　the　mechanism　of　trace　water　molecules　bridging　neighboring　NaSal　molecules　was　revealed　according　to　Fourier　transform　infrared　(FT-IR)　measurements.　The　samples　had　high　viscoelasticity,　for　example,　the　steady-state　low-shear　viscosity　at　a　shear　rate　of　0.001,　η　L　,　of　the　samples　at　W　0　=　32　was　3.3　×　10　5　,　2.0　×　10　4　,　and　6.8　×　10　2　 Pa·s　for　CPC/NaBzs,　CPC/NaNphs,　and　CPC/NaSal,　respectively,　at　25 °C.　The　corresponding　elastic　plateau　moduli,　G′　P　,　were　1.9　×　10　3　,　1.1　×　10　3　,　and　1.1　×　10　2　 Pa,　respectively.　The　temperature　effect　was　examined　for　samples　at　W　0　=　32,　which　were　found　to　retain　high　viscosity　at　higher　temperatures,　for　example,　the　relative　viscosity　to　solvent　cyclohexane,　η　r　,　reached　10　7　and　10　5　for　CPC/NaBzs　and　CPC/NaNphs,　respectively,　at　70 °C.　[Figure　not　available:　see　fulltext.]　©　2019,　Springer-Verlag　GmbH　Germany,　part　of　Springer　Nature.