Twelve individual adult polyps were sampled off Vulcano Island, Italy, from a natural CO2 gradient of decreasing pH nearby a volcanic vent. Three different sampling locations were chosen for this study, representing seawater pH conditions 8.2, 7.9, and 7.6. Total RNAs from three different tissues of the twelve polyps (mouth piece, tentacle and body wall), corresponding to four biological replicates at each location, were isolated. RNAs isolated from the three different tissue samples of each specimen were pooled together in equal amounts before proceeding with polyA enrichment, library preparations and sequencing using Ion Torrent PGM platform. Libraries were barcoded and were sequenced once or twice on six different PGM 318 chips using the Ion PGM 200 Sequencing Kits. Transcriptome sequences coming from one individual from the same sequencing library were pooled together. All reads comprise transcripts from both sea anemone Anemonia viridis and its symbiont Symbiodinium sp.