<p>The current study presents an analytical and experimental investigation of the axial crashworthiness behaviour of cylindrical crash-boxes with a thickness gradient in the lateral direction. Two distinct design approaches are adopted to generate laterally thickness-graded cylindrical crash-boxes, which are fabricated from uniform-thickness circular tubes through a series of machining operations. Axial quasi-static compression experiments are performed on laterally thickness-graded and uniform-thickness cylindrical crash-boxes of equal mass to examine their collapse behaviour and energy absorption characteristics. An analytical model is proposed to describe the collapse mechanism of laterally thickness-graded cylindrical crash-boxes. The proposed model predicts mean crushing force of laterally thickness-graded cylindrical crash-boxes by explicitly accounting for lateral mass redistribution. The experimental results indicate that laterally thickness-graded cylindrical crash-boxes outperform uniform-thickness tubes in terms of crashworthiness. Specifically, a maximum increase of 21% in mean crushing force and an 18% improvement in energy absorption are achieved, without a significant change in the initial peak force. The analytical predictions demonstrate good agreement with experimental observations, with a maximum deviation of 7% in mean crushing force. The study highlights the effectiveness of lateral thickness grading as a design strategy for enhancing crashworthiness and establishes the proposed analytical model as a useful tool for preliminary design and assessment of cylindrical crash-boxes.</p>