This paper describes synthesis and characterization of radioactive gold nanoparticles (198Au-NPs), and explores their utility as a radiotracer for tracing an aqueous phase in a continuous laboratory-scale bubble column at ambient conditions. The performance of the 198Au-NPs as a radiotracer was compared with the results obtained with a conventional radiotracer i.e. bromine-82 (82Br) as ammonium bromide and found to be identical. A tank-in-series with backmixing model (TISBM) was used to simulate the RTDs of the aqueous phase and characterize flow in the bubble column.