An incubation experiment on potassium fixation and availability in six rice soils of West Bengal was conducted at varying levels of added K. Amount of K fixed increased in all the soils with the increase in applied K from 15 to 240 mg kg-1 soil, however, the percentage of added K fixed decreased gradually. The K fixation could still increase upon addition of higher levels of added K beyond 240 mg kg^-1 soil. Illite and smectite dominant Inceptisols with high available and reserve K showed a lower K fixation (4.9 to 39.6 mg kg^-1 soil) as compared to illite dominant Entisols (5.5 to 41.0 mg kg^-1 soil) containing moderate available and reserve K. Conversely, kaolinite dominant Alfisol with low available and reserve K registered the lowest amount of K fixation (2.5 to 14.9 mg kg^-1 soil). Maximum per cent K fixation was observed at 15 mg kg^-1 of added K in all the soils, the more so in Entisols than in Inceptisols and Alfisol. Fertilizer K requirement per unit increase in available K in soil was relatively higher in Entisols and Inceptisols (1.15 to 1.19) and lower in Alfisol (1.06).