The charge transferred between individual particles of varying materials (aluminum, PTFE and nylon) and sizes (3.2-4.8 mm) was investigated using a particle collision apparatus. The collisions were video-recorded and analyzed via a Particle Tracking Velocimetry software to determine the particles' impact velocities and angles. Glancing impacts were found to have a notable effect on charge transfer. Different-material collisions exhibited expected directions of charge transfer. Same-sized nylon collisions revealed that their charge transfer amplified the difference in the particles' initial charges in most cases. Different-sized nylon collisions suggested that sizedependent bipolar charging occurs in individual particle-particle collisions. However, the charging magnitude and direction did not correlate with their size differences, and so additional particle collision experiments with other material types and sizes are needed. This work should be considered as a steppingstone for future researchers to explore particle-particle charge transfer in their respective systems, and develop empirical particle charging models. (C) 2020 Elsevier B.V. All rights reserved.