The dynamic mechanical properties of single polymer composites of poly(methyl methacrylate) (PMMA) reinforced with electrospun PMMA nanofibers of different diameters are reported. The effect of electrospinning parameters on the morphology and diameters of the electrospun high molecular weight PMMA was investigated in order to obtain suitable diameters for the reinforcing fibers. Scanning electron microscopy (SEM) was used to study the morphology and diameters of the nanofibers produced at different electrospinning conditions. It was found that polymer solution concentration influences the diameter of the electrospun nanofibers more than the spinning voltage and spinning distance. SEM analysis of the PMMA nanofibers showed that the fibers had a smooth, regular and cylindrical morphology with no beads and junctions. Effects of the processing temperature for the preparation of the single polymer composites via film stacking were investigated. Dynamic mechanical analysis showed a pronounced improvement in the storage modulus of the composites compared to the matrix.