The effect of highly substituted cationic cetyl trimethyl ammonium bromide (CTAB), less substituted cationic hexadodecyl ammonium bromide (HDAB), CTAB- and HDAB-modified montmorillonite (CTABMONT and HDABMONT), and nonionic surfactants on the rheological properties of methylcellulose (MC) N,N-dimethylformamide (DMF) gels have been studied. The storage modulus of the MC-MDF gels increases with an increase in frequency. During the frequency scan, the storage and loss modulus of MC-DMF gel crosses over each other at two different frequencies. At the crossover points, the loss tangent is found to be unity. The addition of CTAB- and HDAB-modified nanofiller increases in the gel strength of MC-DMF gel. The storage modulus of MC-DMF gel in the presence of CTABMONT is found to be higher than that of CTAB-modified MC-DMF gel. Whereas, the storage modulus of MC-DMF gel in the presence of HDABMONT is lower than that of HDAB-modified MC-DMF gel. On the other hand, the addition of nonionic surfactant (Brij78) decreases the gel strength. (c) 2008 Wiley Periodicals, Inc.