Abstract Amphiphilic cholesteric liquid crystal samples have been prepared using potassium dodecanoyl l-serinate (lKDDS). Laser diffraction was used to determine the twist of the helix in these samples. Detergent concentration and the temperature dependence of the twist have been investigated. The results were found to be similar to those using the detergent potassium dodecanoyl l-alaninate (lKDDA). A binary cholesterogen study has been made using both the detergents lKDDS and lKDDA. The twist was not enhanced and the inter-cholesterogen (detergent) interaction was shown not to be present in these micellar mixtures.