This paper reports the first quantitative comparison of magnetic resonance (MR) and electrical capacitance volume tomography (ECVT) on a 50 mm diameter gas-fluidized bed of silica-alumina catalyst support particles (d(p) = 58 mu m). ECVT data were acquired at a temporal resolution of 12.5 ms and a nominal spatial resolution of 2.5 mm x 2.5 mm x 4.5 mm. Snapshot MR data were acquired at a temporal resolution of 26 ms and a spatial resolution of 1.9 mm x 1.9 mm in the transverse plane and 1.9 mm x 3.8 mm in the axial plane. The particles were doped with water to produce a detectable signal with MR. The two techniques are demonstrated to produce quantitatively comparable time-averaged measurements of the voidage. The bubble frequencies measured from the snapshot images using both techniques were found to be in good agreement. However, the signal intensity inside the gas bubbles was more accurate when measured with MR, and the wake structure could be more clearly resolved using MR. This was attributed to the effect of the smoothing, or point spread function, of the ECVT measurements. An initial estimate of the smoothing in the ECVT has been performed by assuming a Gaussian point spread function.