A melt compounding process was used to prepare hybrid nanocomposites based on natural rubber (NR) and montmorillonite (MMT) modified with octadecylamine. Cured rubber was subjected to complex testing. Most likely modified MMT participates in physical networking of a low-temperature topological region (soft amorphous fraction) of NR networked by low energy junctions. There was a significant difference between behavior of NR containing modified and neat montmorillonite and also those measured at low strain (5-50%) and above 150-170%. Because of this, to optimize compounding process of nanocomposite it is necessary to apply properties those determined under conditions as much as possible close to the usage conditions. (c) 2007 Wiley Periodicals, Inc.