The ability of recently developed novel electrostatic probes to monitor particle charge density and hydrodynamics in freely bubbling two- and three-dimensional fluidized beds of glass beads and polyethylene particles is demonstrated. Particle charge density and bubble properties in the beds were altered by abruptly changing superficial gas velocity or by impulsively adding antistatic agent to the bed. The probes were then utilized to quantitatively monitor the particle charge density and bubble rise velocity. The current signals from the probes responded quickly and significantly to abrupt changes in the superficial gas velocity. By analyzing time-series signals from the probes, the particle charge density and the bubble rise velocity deduced from the probes were found to be of similar order of magnitudes and changed consistently with those obtained from Faraday cup and video measurements. Charge densities from the Faraday cup decreased when an antistatic agent was added, as registered by the probe.