A greenhouse experiment was carried out in 2002 at Jordan University of Science and Technology, Agricultural Experiment Station to examine the effect of potassium fertilization on the response of barley (Hordeum vullgare L.) to different soil salinity levels. Five levels of potassium (0, 0.2, 0.4, 0.6, and 0.8 g K per pot as KCl) and two salt levels (0.75 and 13 ds/m) were investigated in a split plot design with four replications. Soil salinity affected growth and yield component parameters in most of the cases. However, potassium application alleviated the stress condition and significantly (p < 0.05) improved dry matter yield and yield components in barley. The highest dry matter yield (19.63 g/ pot) of barley grown on the very saline soil was obtained in response to the highest potassium level (0.8 g K/ pot). Number of kernels per spike, number of tillers per plant, weight of kernels per spike and total top (shoot) dry weight were all significantly influenced by the main effects and their interaction. The content of nitrogen and Potassium in barley shoot was also increased due to potassium application. In general, the result of this experiment indicated that application of potassium to barley grown on saline soil medium could bring about improvements in yield and yield component parameters, which would otherwise suffer badly.