Crop growth in the reclaimed tideland soils is likely to be inhibited by poor soil physical conditions such as poor aeration and drainage, and high salinity primarily due to high contents of fine particles. Bottom ash which is by-products of power plant using coals can used as soil conditioner of the tideland soils because particle of bottom ash is coarse and their mineral compositions are very similar to soils. In this study, the effect of bottom ash application to tideland soils on improvement of soil conditions and subsequent crop production was investigated in a 50-days of green house experiment. Lettuce (Lactuca sativa) was selected as the target crop as it is known to be very sensitive to salinity stress. Bottom ash was mixed with soil collected from a reclaimed tideland at Goheung, Chonnam province at different rates (0, 5, 10, 20, 30, 40, 50, 75 w/w %). Application of bottom ash substantially decreased EC of the mixture and their effect was proportional to the mixing rate at the initiation of the experiment. After harvest of crop, EC of the mixture decreased further, indicating desalinization during the crop growing period for 50 days. Dry matter yield also responded to bottom ash application, showing increasing tendency with increasing bottom ash rate. Our results suggest that bottom ash can be successfully used as a soil conditioner or amendment in improving soil physical conditions of reclaimed tideland soils.