In order to examine the reduction behaviour of fine iron ores in gas conveyed systems, rise rate of particles temperature are examined and effect of temperature, grain size and feeding rate of iron ore on reduction rate were studied. Results can be summarrized as follows ; 1. After supply of fine ores in gas conveyed systems, their velocity became almost instantaneously equal to the gas velocity. Accordingly the reduction time is nearly equal to the length of reactor tube divided by gas velocity. 2. Calculation of rise rate of particles temperature with assumption of lumped -heat-capacity systems showed that particles temperature became equal to the surrounding temperature in 0.1∼0.3 sec for the grain size below 100㎛. Temperature rise was slow for the paticles with grain size above 100㎛. 3. The reduction rate increased with the increasing temperature and with the decreasing ratio of fine iron ore to gas volume. 4. The fine ores which can be difficultly treated in the fludized bed could be reduced in the gas conveyed systems.