Process for sepg. ethane and heavier hydrocarbons from a gas stream contg methane and ethane as its major components, in which two rectifying sections, each with a reflux stream, are utilised in the demethaniser column. The process comprises (a) cooling the gas stream under pressure sufficiently to form a liq. portion under pressure and a vapour portion under pressure; (b) feeding the liq. portion as a lower feed stream to a fractionating column; (c) expanding a major part of the vapour portion in an expansion means to produce a chilled material and feeding this chilled material as an upper feed stream to the fractionating column; (d) sub-cooling the remaining part of the vapour portion in exchange with cold residue gases from the fractionating column, expanding the sub-cooled vapour portion in an expansion means to produce further chilled material and feeding the further chilled material as lower reflux to a first, lower rectifying section of the fractionating column; and (e) subjecting a small portion of the residue gas to heat exchange (heating), recompression and heat exchange (cooling) and condensing and sub-cooling this in exchange with cold residue gas from the fractionating column, expanding this in an expansion means to provide a very cold material and feeding this very cold material as upper reflux to a second, upper rectifying section of the fractionating column.    Since the residue gas is at a high pressure, it can be condensed at a higher temp. It is then sub-cooled and expanded before returning to the demethaniser as reflux. In addition to the higher ethane recovery at lower compression loads, the present process permits processing of natural gases with higher carbon dioxide concentration than could be tolerated by the previous processes.    ADVANTAGE -   A reflux rate of 10 - 20% increases the recovery of ethane to over 95% with min. increase in compression load, by using the two distinct rectifying sections as opposed to the single rectifying section of previous processes.    .D