BACKGROUND The Structured E-Parenting Support (STEPS) app provides support for parents of children with elevated levels of hyperactivity/impulsivity, inattention, and conduct problems, awaiting clinical assessment by child health services. STEPS will be evaluated in a randomised controlled trial (RCT), as part of the OPTIMA research programme in the United Kingdom. Phase 1 of the OPTIMA programme focused on testing the feasibility of participants’ recruitment and the app's usability. OBJECTIVE To (1) adapt a digital routine clinical monitoring system, myHealthE, for research purposes to facilitate waitlist recruitment; (2) test whether we could use remote methods to screen and identify participants for the RCT quickly and systematically; (3) pilot the acceptability of the proposed recruitment and assessment protocol; and (4) explore STEPS usability to optimise its value for parents. METHODS myHealthE was adapted to handle and screen patients’ data. Feedback on myHealthE was collected from parents and clinicians and information governance reviews were conducted in clinical services planning to host the RCT. Potential participants for the observational feasibility study were identified from new referrals enrolled on myHealthE and via non-myHealthE methods. Descriptive statistics were used to summarise demographic and outcome variables. We estimated whether the recruitment rate would meet the planned RCT sample size requirements (n = 352). In addition to the feasibility study participants, another group of parents were recruited to assess STEPS usability. They completed the adapted System Usability Scale [1] and responded to open-ended questions about the app, which were coded using the Enlight quality constructs template [2]. RESULTS Overall, 124 potential participants were identified as eligible (121 via myHealthE and 3 via non- myHealthE methods). Of those,107 parents were contacted and 48 consented and were asked if, hypothetically, they would be willing to take part in the OPTIMA RCT. Most of the feasibility study participants identified as White (75%). Their children were predominantly male (65%) and had an average age of 8.4 years. During the primary recruitment period (June-July 2021), 19 participants per month (84% of all consented) agreed hypothetically to take part in the RCT (95% CI: 13.5 – 26.1), meeting the stop/go criterion of 18 participants per month to proceed with the RCT. All parents were satisfied or very satisfied with the study procedures. Parents (n=12) recruited to assess STEPS’ usability described the app as easy to navigate and use, with an attractive combination of colours and visual design. They described the content as useful, pitched at the right level and presented sensitively. Suggested improvements included adding captions to videos or making the recorded reflections editable. CONCLUSIONS Remote recruitment and study procedures for testing a parenting intervention app are feasible and acceptable for parents. Parents felt STEPS was a useful and easy-to-use digital parenting support tool. CLINICALTRIAL The RCT that will be conducted in Phase 2 of the OPTIMA programme has been prospectively registered on 18 November 2021; ISRCTN16523503 INTERNATIONAL REGISTERED REPORT RR2-https://doi.org/10.1186/s40814-021-00959-0