Key factors in achieving effective adsorption are the size of the pores relative to those of the adsorbate molecules and often the presence of small metal particles which can confer catalytic activity. While microporous carbons are excellent adsorbents for small molecules they are not as effective for larger species. A new low temperature approach to activation using an oxygen gas pulsing technique to achieve a carbon with controllable meso/micropore structure is described which also minimises metal sintering. The porosity of the samples was analysed by nitrogen adsorption at 77 K. Microporous metal-doped ASC carbon showed significant increases in the level of mesoporosity, its mesopore volume increasing from 0.06 to 0.24 cm3 g-1. However, undoped BPL carbon treated under the same conditions remained unchanged. The catalytic effect of the metals in the ASC carbon is thought to account for the observed mesopore development. At the temperatures used, a continuous oxidative activation yielded no pore widening in either carbon, suggesting that the gas pulsing method is far more effective in increasing mesopore sizes.