The secondary cell wall is a cell wall layer found in some plant cells, most often dead cells and secondary tissue. It is a thick, rigid, hydrophobic cell layer which prevents the transport of most materials into the cell.
The secondary cell wall is made with a cross-netting of cellulose microfibrils and a dense, multimaterial matrix. The matrix is primarily made from lignin and hemicellulose, the former of which causing the cell wall to harden and waterproof.
The secondary cell wall is so rigid that it prevents further growth of the cell. When it is deposited, the cell is expected to die, although there is a chance that it may not.