The present study described the production of three types of non-pyrogenic, highly pure (>99%), single-to-few-layer GO sheets which were found to differ only by their lateral dimensions, without considerably changing neither the surface chemistry nor the thickness, after careful physicochemical characterisation. The mild conditions used during sonication ensured the maintenance of similar surface chemistry properties. We highlighted the need for using complementary techniques to characterise the physicochemical properties and to reduce potential experimental errors and/or inaccuracies. Combining three microscopic techniques, we found that the produced l-GO flakes had lateral dimensions varying between 1 and 30 µm, s-GO flakes ranged between 50 nm and 2 µm and us-GO flakes were smaller than 500 nm. Therefore, we showed that non-pyrogenic GO flakes can be produced with controlled lateral dimensions. Future studies should investigate how lateral dimension of GO sheets may affect their biological impact and their cellular, tissue and whole body interactions.