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- 4.055mM) 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±14.59nm were formed using 1.53mM gold concentration. DLS data showed that AuNPs with hydrodynamic diameter 55.22 ± 42.86nm 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 ±8.21nm were formed when higher gold (III) precursor concentrations (4.055mM) 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.