A thermal diffusion column reactor (TDCR) with carbon rod as pyrogen was used to methane pyrolysis to produce gaseous light hydrocarbons and oily products, since TDCR has temperature gradient and therefore a separation effect on products. Product selectivity was adjusted by changing direction of methane gas flowing. At 1470 K and downwardly flowing of methane at 60 ml/min, selectivity of C-2 products kept around 44.6% during the 8 h reaction, oil selectivity was around 53.8%. When supplying methane in upwardly flowing direction, oil selectivity was increased to around 75%. The effect of flowing direction was ascribed to thermal diffusion and convection of products in the TDCR due to the presence of temperature gradient. Moreover, a detailed discussion on coke deposit was made. (c) 2007 Elsevier B.V All rights reserved.