RH-34 is a compound which acts as a potent and selective partial agonist for the 5-HT2A serotonin receptor subtype. It was derived by structural modification of the selective 5-HT2A antagonist ketanserin, with the 4-(p-fluorobenzoyl)piperidine moiety replaced by the N-(2-methoxybenzyl) pharmacophore found in such potent 5-HT2A agonists as NBOMe-2C-B and NBOMe-2C-I. This alteration was found to retain 5-HT2A affinity and selectivity, but reversed activity from an antagonist to a moderate efficacy partial agonist.