Cellulose acetate nanofibers were electrospun under a controlled atmospheric environment to establish the impact upon the reproducibility of fabrication. The effects of process temperature and process humidity on the resulting fibre morphology were investigated. The results obtained from SEM indicated the expected correlation of decreasing average fibre diameter with increasing process temperature. For this polymer-solvent system the average fibre diameter decreased from 360nm to 284nm for process temperatures 17.5°C and 32.5°C respectively. A correlation was also observed whereby the fibre diameter increased with increasing humidity. The fibre diameter increased from 300nm to 352nm for process humidity 20% RH and 70% RH respectively. In addition, the relative humidity levels during the electrospinning process appeared to be the dominant factor in determining the level of bead formation. This is most likely due to the effective rate of evaporation which determines the stability of the chain entanglements due to flight time. This unexpected but notable observation has given new possibility for the controlling of beading nanofiber systems and has highlighted the importance of controlling atmospheric conditions during the electrospinning process. This is particularly relevant to the membrane industry where beading would result in a poor quality of membrane structure.