Technical Abstract: Barley (Hordeum vulgare L.) is considered moderately salt-tolerant compared to other cereals. Recent transcriptome studies on salinity stress response in barley indicated regulation of jasmonic acid (JA) biosynthesis and JA-responsive genes by salt stress. From that observation it was hypothesized that JA is involved in the adaptation of barley to salt stress. Here we tested that hypothesis by applying JA to barley plants and observing the physiological response and transcriptome changes. Photosynthetic and sodium-ion accumulation responses were compared after 1) salinity stress, 2) JA treatment, and 3) JA pretreatment followed by salinity stress. The JA-pretreated salt-stressed plants accumulated strikingly low levels of Na+ in the shoot tissue compared to untreated salt-stressed plants. Also, pretreatment with JA partially alleviated photosynthetic inhibition caused by salinity stress. Expression profiling after a short-term exposure to salinity stress indicated a considerable overlap between genes regulated by salinity stress and JA application. Three JA-regulated genes, arginine decarboxylase, rubisco activase, and apoplastic invertase are candidates involved in salinity tolerance mediated by JA. This work provides a reference dataset for further study of the role of JA in salinity tolerance in barley and other plants species.