This work deals with the synthesis of organically modified Ni-Al layered double hydroxide (LDH) and the effect of Ni -Al LDH loading on the rheological behavior of PMMA/Ni-Al LDH blends prepared by solvent blending method. Firstly, Ni-Al LDH was synthesized by co-precipitation method at constant pH using their nitrate salts and subsequently modified using sodium dodecyl sulfate (SDS). Then, PMMA blends with various LDHs content (3 and 5 wt.% with respect to PMMA) were prepared by solvent blending method using methylene chloride as a solvent. The structural properties of the modified Ni -Al LDH were characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM) and FTIR analysis. The XRD analysis reveals that the d-spacing value of the modified LDH increases to 135 nm from 0.80 nm for the unmodified LDH, which confirms the insertion of SDS molecules into the Ni-Al LDH interlayers. The presence of sulfate groups in the modified LDH is confirmed by FTIR analysis. The rheological characteristics of PMMA/Ni- Al LDH blends were performed on rotational rheometer using HAAKE Rheostress RS1 with cup and cylinder geometry at room temperature. It is observed that the rheology of PMMA blends is affected by increasing LDH loading as well as shear rate. All the PMMA/LDH blends exhibit enhanced shear viscosity as compared to neat PMMA. In addition, the obtained rheological data are fitted with various models, like Power law, Herschel-Bulkley, Casson, Sisko, Cross, and Carreau models to explain the rheological behavior. The results clearly indicate that the Herschel-Bulkley model fits the rheological data better than other models. (C) 2014 Elsevier B.V. All rights reserved.