Religiosity has been identified as one of the factors that affects individuals' ethical decision-making. While many studies have focused on religiosity's impact to ethical behaviour, the reasons behind this impact are diverse in the literature. Using a quantitative approach with the focus on Islamic religiosity, this paper presents ongoing Ph.D. research that examines several factors in behaviour at work, which could be affected by Islamic religiosity. The hypothesis is that religiosity mediates factors such as moral judgment, perceived importance of ethical issues, ego strength, conscience, and the intention to positively impact ethical decisions in the workplace. The survey designed for this Ph.D. research has been pilot tested on 22 Muslims working in Malaysia, and the results of this pilot study support the use of the instrument on a main sample to test the hypothesis.