Ported wall extensions are important hydraulic structures used to reduce crosscurrents in upper approaches to locks. The effect of such extensions located upstream of a solid guard wall on flow characteristics depends on many factors, including geometric and hydraulic pa-rameters. In this study, the hydraulic performance of ported wall extensions was experimentally investigated in terms of the permeability co-efficient, expanding angle, extension length, and flow depth. The results demonstrate that the dimensionless maximum transverse velocity is closely related to the permeability coefficient, expanding angle, and flow depth. By contrast, the dimensionless eddy length mainly depends on the permeability coefficient, expanding angle, and extension length. Furthermore, the optimum permeability coefficient increases with the expanding angle or flow depth, and it is approximately constant for different extension lengths. These results have the potential to provide direct guidance for the design of effective ported wall extensions in upper approaches to locks.