Refined Jatropha curcas L. oil (JCO) and methanol were used as the reactants for the transesterification reactions in a Radleys reactor in the presence of a heterogeneous ash catalyst derived from the waste aquatic plant Lerma perpusilla Torrey. Physical characterization of the catalyst showed partly crystalline behaviour and a moderate surface area 9.622 m(2) g(-1). The L. perpusilla Torrey ashes obtained from traditional combustion method were further calcined at 550 +/- 5 degrees C before use. In addition to other non-metal and metallic constitutes the ash contains 11.3% potassium which attributed to its catalytic behaviour. The cumulative mass fraction of 89.43% of the oil was converted to biodiesel at 65 +/- 5 degrees C in 5 h at 1:9 M ratio of oil to alcohol with 5% of the ash as catalyst. The biodiesel (FAME) so obtained were characterized using appropriate ASTM methods and found within the defined standard limits. The catalyst could be reused upto 3-times but there is a reduction of efficacy by about 25% for 3rd consecutive batch reaction. The activation energy was calculated for FAME and found to be 29.49 kJ mol(-1). (C) 2013 Elsevier Ltd. All rights reserved.