Abstract: This study examines the role theory and audit expectation gap and the performance of internal auditors in the prevention of financial misappropriation of funds in the public sector of South South Nigeria. Audit expectation gap is the difference between the levels of expected performance as envisioned by the users of financial statements and by the independent accountant. To achieve the objective of this paper, data were collected from primary and secondary sources. The primary source was generated from a well structured questionnaire administered to 120 internal auditors in Bayelsa State and Cross Rivers State in South South Nigeria. The researchers only collected 96 usable questionnaires that were analysed using Spearman rank order correlation coefficient, Mann-Whitney U test and descriptive statistics. The study revealed that there is a significant relationship between audit expectation gap and internal auditors in the prevention financial misappropriation of funds in the public and there is significant difference between the perceptions of auditors and users whether the intervention of management hinders the effective performance of internal auditors in South South, Nigeria. On the basis of the findings, the paper concludes that internal auditors in the public sector in Nigeria is not performing the audit responsibility with all level of professional and technical expertise as expected by the society. This is why there is wide spread misappropriation of public sector funds and massive corruption in Nigeria. Therefore, the paper recommends amongst others that internal auditors in All Ministries, Departments and Agencies (MDAs) should have the requisite professional qualification (example, the Institute of Chartered Accountants of Nigeria), the issuance of new audit standards for public sector accounting system
