<b>Effect of Determinants of Financial Reporting Timeliness on Reporting Timeliness An Empirical Study of Nigerian Banks</b> This study assesses the relationship between the determinants of financial reporting timeliness of Nigerian banking industry. Specifically, the study ascertains the effect of bank age on the timeliness of financial reporting in Nigerian banks examines the effect of the size of audit firm on the timeliness of financial reporting in Nigerian banks. Ex Post Facto research design was adopted. The population of the study will consists of deposit money banks quoted on the Nigerian Stock Exchange. The study covered eleven years of annual reports and accounts of these companies from 2011 to 2019. Data were extracted from annual reports and accounts of the sample population. Hypotheses formulated for the study were tested using the Regression analysis with aid of E view version 9 software package. From the test conducted, the study found that the age of the bank has a significant effect on the timeliness of financial reporting. The size of an audit firm significantly influences the timeliness of financial report because auditors cannot change the timeliness of financial report without the corporation of their client. To mitigate the problem of reporting lag in financial reporting in the Nigeria banking sector, there should be harmonization of the various conflicting provisions regarding timeliness as currently contained in the various enactments. Financial Reporting Timeliness, Age of a bank, and Size of audit firm 16-24 Issue-3 Volume-5 Ogbodo, Cy Okenwa | Jiagbogu, Nwadiogo K