An online X-ray diffractometer rig connected to flow cell has been set up for the purpose of monitoring phase transition in FAME waxes. This system involves a slurry flow loop from a 100mL reactor pumped by means of a peristaltic pump. The temperature of the glass-lined, jacketed reactor is controlled by means of fluid exchange with a Julabo F32 HL heat exchanger. The Julabo heat exchanger is controlled by computer using Julabo Easytemp Professional software. To allow for the monitoring of nucleation temperatures during crystallisation run, the temperature / turbidity profile is also measured through in-reactor temperature and turbidity probes and recorded on computer by Labview software. The flow loop transports initially the supersaturated solution and on crystallisation transports the solvent / wax slurry and passes through the X-ray diffractometer unit. It is therefore possible to attain X-ray diffraction peaks for the wax crystals produced. Inel software is used to monitor and record on computer the data generated relating to X-ray diffraction patterns achieved from the reflection of the incident X-ray caused from its disruption by a solid-state ester wax crystal. As all homogenous crystalline materials produce a specific signature diffraction pattern when disrupting X-ray beams, this system allows the identification of the polymorphic form of crystals precipitating from the formulated solutions. Where a shift in the X-ray diffraction pattern is detected it indicates the presence of a different crystal polymorph in the ester wax. The objective is to establish the operating conditions which affect polymorph stability and give rise to phase transition in the ester waxes to determine the influence of solution environment on polymorphic form and phase transition of ester waxes crystallising from FAME solutions.