Thin shells are lightweight, efficient structures that can support very high buckling loads. However, unlike columns and plates, shells usually have a very unstable post-buckling behaviour that strongly influences their buckling characteristics. Axially compressed cylinder may be one of the last classical problems in structural mechanics for which it remains difficult to obtain close agreement between careful experiments and the best predictions from numerical modelling, and therefore much more research is needed on this subject. Within this investigation, 18 glass fibre composite shells with wall thickness of 1.1 mm, 0.3 m and 0.5 m diameters and various lengths have been produced along with flat specimens for determination of elastic properties of the material. The cylinders were repeatedly loaded until post-buckling and load-shortening curves and pictures of buckling mode shapes have been registered. Finite element models of the specimens have been developed in ABAQUS finite element package and non-linear explicit dynamic analyses have been performed for comparison with experimental and analytical results. Gradually improving the finite element model and adding artificial initial imperfections resulted in good agreement between the experimental and numerically obtained critical loads. The buckling modes observed during the experiments are in good agreement with the results of finite element simulations as well.