Ethyl-cyanoethyl cellulose [(E-CE)C] can form lyotropic cholesteric liquid crystals in acrylic acid (AA) and the liquid crystalline behavior is influenced by the concentration and (E-CE)C molecular structure. The critical concentration C1 increases with increasing (E-CE)C molecular weight and is also influenced by the degree of substitution for cyanoethyl. The C1 is lowest when the degree of substitution for cyanoethyl is 0.26. The pitch of cholesteric phase decreases with increasing both the (E-CE)C concentration and the degree of substitution for cyanoethyl and can not be influenced by the molecular weight of (E-CE)C in the molecular weight region of 6x10(4) - 5x10(5).