Attentional biases to suicide-related stimuli are thought to be related to suicidal thoughts and behaviors (STBs). The suicide Stroop task has been used to measure said attentional biases; however, recent investigations have introduced doubt regarding its psychometrics. This prospective study investigated the psychometric properties of a web-based version the suicide Stroop. Participants were N = 591 United States adults with a history of STBs recruited through an online survey recruitment platform. Participants responded to questionnaires and completed the suicide Stroop on their personal computers at two time points, one week apart. Results indicated that mean reaction times to suicide-related and negative stimuli demonstrated acceptable internal consistency reliability at both time points. In addition, evidence was provided for the temporal instability of these stimuli types over time. Neither stimuli type demonstrated evidence of convergent or predictive validity. These results suggest that adaptations to the suicide Stroop thereby improving its psychometric properties is warranted.