Coal carbonization for various kinds of single coals, coal blends, and operating conditions has been carried out in a movable-wall test coke oven (0.18 mW x 0.4 mH x 0.45 mL) to investigate the coking pressure behavior. The internal gas pressure and its corresponding temperature at the coal charge center were measured using the probe with thermocouple. internal gas pressure of single coals increases with an increase of coking capacity and a decrease of volatile matter content. The internal gas pressure and the coke strength of coal blends mixed with single coals mainly depend on the blending ratio of a given coal in coal blends. With decreasing moisture content of coal blends, heating rate at the coal charge center decreases and internal gas pressure exponentially increases. Bulk density of coal blends exponentially increases with decreasing moisture content, Also, coke strength linearly increases with a decrease of coal moisture content. With increasing heating-wall temperature, internal gas pressure of coal blends increases, but coke strength decreases.