This study focused on the development of a mathematical model required for estimating the number of adopters of ICT devices among libraries located in Nigeria. Data for this study was collected from 121 respondents selected based on a research survey approach using simple random sampling. 9 ICT devices were identified, namely: PCs, printers/fax machines, search engines, e-library systems, bulk SMS services, library management systems, bar/QR code readers, projectors and video conferencing. The results showed that the earliest ICT devices were adopted for use in 1997, such as: PCs, printers/fax machines and search engines. The remaining ICT devices were adopted in 2000, such as: e-library, bulk SMS services, library management system, bar/QR code readers, projectors and video conferencing. Polynomial functions of degree, m was used to formulate the mathematical model for the adoption of each ICT device identified based on the cumulative frequency of yearly adopters.