NOVELTY - Method (M1) for naphthalene removal from a gas stream involves (a) gasifying carbon containing raw material to produce a gas stream comprising carbon monoxide and hydrogen as main components, and at least naphthalene as impurity; and (b) contacting the gas stream from which naphthalene is to be removed with a first porous solid adsorbent material comprising benzene.    USE - For producing hydrocarbons or their derivatives (claimed).    ADVANTAGE - The adsorption by the adsorbent material is reversible so that the material can be reused and naphthalene and possibly benzene recovered after regeneration, thus the reversible adsorption is cost efficient. The adsorbents are easily regenerated, chemically very stable, and do not contain any poisons or environmentally unacceptable components. The solid adsorbents comprising benzene provides surprisingly good results for naphthalene removal which can be implemented after gasification of carbonaceous biomass and before the temperature of the gas so produced reaches a temperature below which naphthalene no longer remains fluid. The method for benzene and naphthalene removal can be incorporated to any process where naphthalene and/or benzene cause trouble or are otherwise undesirable; and also can be applied to a process where there is a need to remove naphthalene alone.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for producing (M2) hydrocarbons or their derivatives from biomass raw material, involving (a) gasifying the biomass raw material in the presence of oxygen to produce a gas comprising carbon monoxide, carbon dioxide, hydrogen and hydrocarbons; (b) removing naphthalene from the gas obtained in step (a) by contacting gas with the first porous solid adsorbent material comprising benzene; (c) adjusting the hydrogen to carbon monoxide ratio; (d) converting in a synthesis reactor at least a significant part of the carbon monoxide and hydrogen contained in the gas into a product selected from hydrocarbon composition and their derivatives; and (e) recovering the product hydrocarbon or its derivative.