Abstarct: Abstract The rising of bubbles is an important and fascinating topic in the field of fluid mechanics, with numerous industrial applications including water purification, oil extraction, agriculture (in irrigation), papermaking, and mining (for particle and mextal separation). This study is an experimental investigation of the behavior of air bubbles rising in quiescent fluids. The studied fluids include Newtonian fluids (water and glycerin) and non-Newtonian viscoelastic fluids. In this study, bubbles were generated by injecting air at various flow rates into the fluid, and their motion from the point of detachment from the needle to the fluid's surface was recorded using a high-speed camera. Subsequently, the captured images were analyzed using image processing methods to extract bubble characteristics such as volume, trajectory, terminal velocity, and shape. The analysis of the results revealed that bubble properties, such as terminal velocity, volume, shape, and trajectory, strongly depend on fluid rheological properties, needle internal size, injected air flow rate, and laboratory environmental conditions. For example, increasing the injected air flow rate in the G18 needle from 300 to 900 ml/h leads to an increase in the equivalent diameter of the bubble from 0.56 to 0.70 cm in non-Newtonian fluid and the equivalent diameter of the bubble in Newtonian fluid from 0.55 to 0.56 cm increased and also caused an increase in the final velocity of the bubble from 15 to 22 cm/s in non-Newtonian fluid and an increase in the final velocity from 20 to 24 cm/s in Newtonian fluid. Furthermore, an increase in the needle internal size resulted in larger bubble volumes and, consequently, higher rising velocities. By increasing the inner diameter of the needle from G21 to G18, the equivalent diameter of the bubble increased from 0.48 to 0.7 cm and the terminal velocity of the bubble increased from 20 to 22 cm/s in non-Newtonian fluid. In this experiment, due to the high viscosity of the fluids, the bubble trajectories were nearly straight lines. However, the deviation of bubble paths from the straight line was more pronounced in Newtonian fluids compared to non-Newtonian ones. By comparing the results obtained from both types of fluids, it was observed that in viscoelastic fluids, bubble volumes under similar conditions (with the same flow rate and needle size) were larger, and the rising velocities of bubbles were also greater compared to Newtonian fluids. For example, in the G21 needle at a flow rate of 20 ml/h, the bubble volume in non-Newtonian fluid was 40% higher than the bubble volume in Newtonian fluid, and the rising velocities of bubbles in Newtonian fluid was 37% higher than the rising velocities of bubbles in non-Newtonian fluid. Finally, by calculating the drag coefficient and plotting the drag coefficient as a function of the Reynolds number, it was observed that at Reynolds numbers less than 10, the drag coefficient decreased with increasing Reynolds number. However, for Reynolds numbers greater than 10, this trend was slower and more irregular.