Assessment of cognitive function via the Internet is possible, but technically complex in comparison to self-report questionnaires. Self-report measures of cognitive function also have problems, but are easy to implement online and may give valuable insights, especially into people’s own experiences of everyday cognitive problems. For example, a number of online studies have examined self-reports of memory problems. “Executive function” describes a collection of processes making up the central executive component of the working memory model, including planning, task coordination, impulse control, and attention. Deficits in executive function are of clinical and scientific interest. A number of objective cognitive measures are believed to tap aspects of executive function. In addition, self-report questionnaires measuring executive deficits (e.g. the Dysexecutive Questionnare; DEX) have been developed and appear to have a degree of validity. This project involved creation and validation of a short, public domain self-report measure of executive function suitable for administration via the Internet. We created a 6-item self-report measure addressing different facets of executive function as a short web-based form. This was completed by 78 undergraduate participants (18 men, 60 women), who also completed the self-report DEX and three objective cognitive tasks: reverse digit span, a semantic fluency task, and a semantic fluency task with inhibition. All data were acquired in a laboratory setting. The six items appeared to form a factor-univocal scale with adequate internal consistency (alpha=.785). Scale scores correlated strongly and significantly with the DEX (r=.677) indicating that the two measures have much in common. They correlated negatively with all three objective measures of executive function (r=-.284, r=-.353 and r=-.416 respectively), indicating higher scores are associated with poorer performance. The pattern of associations between the DEX and these three measures is similar, though the correlations for the new scale are stronger. We present the new scale, ‘WebEXEC’, as a quick and reliable online self-report measure of executive function. While further validation work is planned, the evidence so far suggests the measure has a degree of validity and may be suitable for use in Internet-mediated research projects.