Abstract: A cell separator plate for separating fuel cell units in fuel cell stacks, the separator plate having a peripheral seal structure extending from each face completely around its periphery and a electrolyte seal structure extending from each face and having a generally flat face spaced inwardly from the separator plate peripheral seal structure and extending completely around the separator plate forming a separator plate/electrolyte seal with an adjacent electrolyte under cell operating conditions, and a peripheral compartment between the separator plate/electrolyte seal and separator plate peripheral seal between adjacent separator plates. The peripheral compartment may contain active electrolyte which may be wicked into the electrolyte matrix through edges of the matrix directly exposed to the peripheral compartment. The peripheral compartment may contain an inert gas to ensure active electrolyte containment within the electrolyte matrix.