Air-water-fiber flows are found in the pulp and paper industry in a variety of unit operations such as flotation deinking of recycled paper and fiber bleaching. Vertical bubble column reactors are often used for these operations due to low cost, ease of operation, and high interfacial areas. The complex hydrodynamics of bubble columns are difficult to understand due to the presence of many different phenomena occurring in the flow. Therefore, it is difficult to scale up the information gathered from research for industrial sized applications. The current study experimentally investigates the effects of fiber mass fraction, superficial gas velocity, fiber type, fiber length, and distributor plate open area on gas flow regime, and overall and local gas holdup in a 32.1 cm diameter semi-batch bubble column. Three different Rayon fiber lengths (L = 3, 6, 12 mm) and three different cellulose (natural) fiber types are experimentally studied over a range of superficial gas velocities (U[Subscript g] [Less than or equal to] 20 cm/s), fiber mass fractions (0 [Less than or equal to] C [Less than or equal to] 1.8%), and distributor open areas (A = 0.49, 0.95, and 2.03%). Local gas holdup is determined by pressure drop measurements at several axial locations spanning a height of ten column diameters (H = 321 cm). Overall gas holdup is determined from the pressure difference between the top and bottom pressure transducers. The Zuber and Findlay drift flux model is used to determine the gas flow regime. Fiber mass fraction had the most significant influence on overall and local gas holdup, where increasing fiber mass fraction decreased gas holdup. Superficial gas velocity has different effects on gas holdup for flows that demonstrate three regimes (homogeneous, transitional, and heterogeneous) and flows that were heterogeneous for all superficial gas velocities (pure heterogeneous). Local gas holdup trends showed two local maximum gas holdup values and the existence of recirculation cells within the flow. Their location and size depends on fiber type and distributor plate open area.