The widespread adoption of mobile phones has increased the potential of mHealth to improve health communication and health outcomes because these devices could serve as a ubiquitous and affordable means to disseminate health information to large populations. Given that mHealth apps offer free or limited trials as part of promotional strategies, potential users' trialability is a critical step of the preadoption process. Drawing from Rogers' diffusion of innovation theory, this study examines the relationships of adopters' perceived characteristics of mHealth apps (i.e., relative advantage, complexity, compatibility, and observability) with their trialability. It further investigates how the perceived control of mobile devices and trialability of mHealth apps influence two dimensions of mHealth literacy, namely seeking and appraisal of health information. This web survey recruited 295 young mHealth app users from a Singaporean university. Results of partial least squares regression show that the observability of mHealth apps is the only factor positively related to mHealth trialability. Perceived control of mobile devices and trialability of mHealth apps are positively associated with seeking and appraisal of health information. Practical and theoretical implications to mHealth are discussed.