Electrospinning is a versatile method for manufacturing polymer-based multi-functional and high-performance nanofibrillar network. Two important characteristics, namely minimum diameter variation and bead area, render the nanofibre mats acceptable for many membrane type applications, but the relationship between processing parameters and microstructures is still not well understood. This article outlines a systematic study via the design of experiments in the context of selecting process control parameters while electrospinning nonwoven mats of nanofibres from poly(l-lactic acid). The goals are to obtain a robust set of parameters to reduce the variation in product quality by performing the minimum number of experiments. A desirable combination has been found to be low concentration of polymer solution, low feed rate, comparatively high applied voltage and a large distance between the collector and the needle. However, a low concentration of polymer solution may result in some bead formation if other factors are not changed accordingly.