Abstract: A surface for the attachment and growth of cells is prepared by first grafting polyacrylic acid chains to a fluorocarbon polymer substrate so that its weight increases by between 0.1 % and 20%. The surface is then treated with concentrated sulphuric acid under such conditions that will separately decarboxylate, aromatize and sulphonate an effective proportion of the grafted polyacrylic acid chains before being dried, soaked in a concentrated acid and brought to a substantially neutral pH for cell attachment and growth thereupon. The surface may also be used as a human tissue implant.