Abstract: A gravity cross-flow separator of the type comprising mutually parallel spaced-apart plates defining a substantially horizontal liquid flow path between each pair of adjacent plates for passing a liquid to be treated by gravity separation, the plates being inclined relative to a horizontal plane and defining upper and lower gutters extending substantially in the direction of liquid flow for collecting components separated from the treated liquid and disposed above and below the flow path, respectively, is improved in that the upper gutters of each flow path are in facing alignment with the lower gutters of the same flow path.