An experimental apparatus and approach were developed to measure the instantaneous changes in pressure gradient and solid volume fraction with the time along a collapsing fluidized bed. Measurements were made for a single fluid cracking catalyst. The pressure transducer and X-ray data were in excellent agreement. These data along with a straightforward one-dimensional description of both gas and solid phases were used to obtain the solid stress modulus and the drag coefficient for the catalyst powder in the solid fraction range between minimum fluidization and loose packing.