A flow distributor for a liquid descending in a vertically elongated mass transfer column, a mass transfer column employing the same, and a method of treating a fluid stream in the mass transfer column is provided. The flow distributor includes a central distribution member for passing liquid to a plurality of outwardly extending side arm members, which, in turn, feed the liquid into a plurality of distribution troughs located below the elongated side members. The distribution troughs, which may be oriented substantially perpendicularly or substantially parallel to the elongated side members, include a bed of packing material disposed therein. Use of such distributors in vapor-liquid or liquid-liquid columns results in more uniform horizontal distribution of the liquid across the diameter of the column.