By utilizing the extended Technology Acceptance Model, this empirical study investigates the influence of the demographic characteristics of age, gender and education on adoption and use of e-government services in the context of Sri Lanka. The Technology Acceptance Model (TAM) was extended by adding additional constructs of national culture, trustworthiness and awareness. The extended model was validated utilizing 898 responses collected from five provinces selected randomly. Collected responses were analyzed by Structural Equation Modeling (SEM) approach and the empirical findings of the multiple group analysis explore; the influence of age and gender is invariant across the different age and gender groups of users while the non-invariant influence exists among the diverse educational groups of users. This is the first study, which has focused to explore the influences of demographic characteristics towards the adoption and use of e-government services. Thus, implications provided in this study can help for policy makers and relevant authorities to enhance the level of adoption and use of e-services.