Background: The development of technological applications within psychotherapy has opened up new opportunities for mental health professionals (MHPs) to address client need. Despite the clinical efficacy and utility of evidence-based electronic interventions, MHPs' engagement with these interventions remains poorly understood.

Objective: The aim of the current study was to develop and conduct a preliminary psychometric investigation of the measurement properties of the electronic-therapy attitudes and process questionnaire – therapist version (eTAP-T). Based upon the theory of planned behaviour (TPB), the eTAP-T measures factors related to MHPs' engagement with e-interventions for clients' mental health concerns.

Methods: Participants were 222 practicing MHPs who reported being in direct contact with clients. Participants completed the eTAP-T and related measures with a subsample of 40 participants completing a two-week follow up questionnaire.

Results: Exploratory factor analysis with item reduction resulted in a 12-item eTAP-T, with four factors accounting for 82% of variance. The four factors (subjective norms, perceived behavioural control, attitudes and intentions) were consistent with the four TPB domains. The eTAP-T demonstrated satisfactory validity and reliability as per the consensus-based standards for the selection of health measurement instruments.