The performance of Pistia Stratiotes for organic matter and ammoniacal nitrogen removal was monitored in a surface sequencing baffled steep flow constructed wetland reactor at various intensity of sunlight. The reactor has 5 compartments of various sizes (C1�C5). Pistia Stratiotes were planted in all the compartments of the reactor. Influent wastewater was applied to compartment 1 (C1) at a hydraulic loading rate (HLR) of 10.2m3/m.d�1 and hydraulic retention time (HRT) of 6 hours. The average organic loading rate (OLR) and ammonia loading rate (ALR) were in the range 6�8 g COD/m3.m.d�1 and 0.15�0.25 gNH+ 4 -N/m3.m.d�1 respectively. Reactor temperature was daily monitored alongside sample collection at 9 AM, 12 PM, 3 PM and 7 PM respectively for 7 days. On day 4, (3 PM at 35.9�C), NH+ 4 -N removal reached 94. COD removal reached 50�55 between 9 AM and 12 PM but fluctuated between 5�14 at 7 PM from day 1 to day 7. This study demonstrates that temperature can influence the performance of Pistia Stratiotes. © 2016 Taylor & Francis Group, London.