Aluminum has been investigated at multi-Mbar pressures through planar impacts generated by guns and explosives, and ablatively driven shocks from high energy lasers. Because it is well characterized, it is often used as a reference in relative Hugoniot measurements. To determine equation of state measurement capabilities on the Sandia Z accelerator, Hugoniot states of type 1100 aluminum were determined in the 1.8 to 4.5 Mbar range for comparisons to published data. Ablatively driven shocks on 6.5 mm diameter samples were measured using velocity interferometry and laser based shock arrival sensors. In each experiment, both shock and particle velocities were independently measured to determine Hugoniot states. Many of the experiments performed had multiple measurements of these two parameters for redundancy and diagnostic validation. Results indicate agreement with the extrapolation of a previously established, lower pressure, Hugoniot within error bounds representing the experimental uncertainties. ©2000 American Institute of Physics.