Electronic Journal of Differential Equations, Vol. 2019 (2019), No. 36, pp. 1-9. Title: Nonlinear Fredholm equations in modular function spaces Author: Mostafa Bachar (King Saud Univ., Riyadh, Saudi Arabia) Abstract: We investigate the existence of solutions in modular function spaces of the Fredholm integral equation $$ \Phi(\theta) = g(\theta) + \int^1_0 f(\theta,\sigma, \Phi(\sigma)) \,d\sigma, $$ where $\Phi(\theta), g(\theta)\in L_{\rho}, \theta\in [0,1], f: [0,1]\times[0,1]\times L_{\rho}\to \mathbb{R}$. An application in the variable exponent Lebesgue spaces is derived under minimal assumptions on the problem data. Submitted March 13, 2018. Published March 05, 2019. Math Subject Classifications: 46A80, 47H10, 45G05. Key Words: Electrorheological fluids; fixed point; Fredholm equations; modular function spaces; variable exponent spaces.