Room temperature ionic liquids (ILs) are a class of complex fluids with valuable physical properties. Therefore, the investigation of dynamics of IL is vital for the fundamental understanding of their physical nature as well as for the successful engineering design in their applications. We succeeded in performing the first in-depth rheological studies of two ionic liquids of different nature in a wide frequency and temperature range (up to the glass transition and beyond), utilizing advanced techniques with an oversampling procedure and with adjustment of the instrument compliance. The important physical parameters of IL, such as Vogel temperatures, fragility, fractional free volume at the glass transition temperature, and volume expansion coefficient, were determined by rheology. Deviation from the Vogel-Fulcher-Tammann behavior is detected in the vicinity of the glass transition. The master curves of dynamic moduli for both IL show systematic deviations from Maxwell behavior in the low and high frequency domains. The calculated spectra exhibit a broad relaxation time distribution, which can be approximated by two non-Maxwellian modes. We attribute the fast mode to the motion of single ions, while the slow mode might reflect the cooperative motion of ions. Our results are supported by recent dielectric and optical studies, theoretical models, and simulations, which reported dynamical heterogeneities in IL. (C) 2011 The Society of Rheology. [DOI: 10.1122/1.3528651]