In this study, gold nanoparticles (AuNPs) were synthesized by using aqueous extract of Elaise guineensis (oil palm) leaves without addition of any external stabilizing agent. Effects of precursor concentrations (0.51 mM- 4.055 mM) on SPR absorbance and AuNP particle size distribution were investigated. The synthesis reaction was monitored by measuring time-variant SPR spectrum of the reaction medium with a UV-vis spectrophotometer. Biosynthesized AuNPs were characterized using TEM, DLS, UV-vis and FTIR spectroscopy. TEM image analysis showed formation of predominantly spherical gold nanoparticles with mean particle diameter of 27.89±14.59 nm were formed using 1.53 mM gold concentration. DLS data showed that AuNPs with hydrodynamic diameter 55.22 ± 42.86 nm were formed, indicating formation of multilayer coatings of biomolecules present in the leaf extract on nanoparticles. Spherical, triangular, pentagonal and hexagonal gold nanoparticles with mean particle diameter 22.88 ±8.21 nm were formed when higher gold (III) precursor concentrations (4.055 mM) were used. FTIR analysis revealed that carboxylic and phenolic compounds present in leaf extract played dual roles as reducing and stabilizing agents during synthesis of AuNPs. © 2016 The Authors.