An experimental technique called bundle-debonding, has been developed for characterizing the interfacial adhesion of fibre bundles and matrix. The specimen is double-notched and contains a partially embedded fibre layer in between the notches. When a tensile load is applied at the specimen ends, the load transfer across the notch and between two pieces of matrix, occurs through the interface between a single layer of fibres and matrix. Kevlar-29 (Kelvar is a registered trademark of E.I. duPont de nemours) fibre tows were used in conjunction with a solid phenolic resin to fabricate the specimens. Experiments were conducted at various embedded lengths resulting in interfacial debond. A simple shear-lag analysis was carried out to determine the interfacial shear strength. The interfacial shear strength of Kevlar-29/phenolic resin has been determined to be 1 5 MPa. This technique is promising for application on several fibre/matrix systems, specially for fibres of extremely low nominal diameter, supplied as tows.