The overall kinetics of formation of the Au NPs, estimated when various metrics reached a steady state, are rather slow using ethanol compared to the case where glycerol is used. This observation is in agreement with the more rapid formation of red colloidal dispersions (which can be observed with the naked eye) when glycerol is used compared to the use of ethanol only. When mixtures are used, and even with small amount of glycerol such as 2 v.% glycerol with 18 v.% ethanol, an overall faster appearance of a red colloidal dispersion can be observed with the naked (Amax) 1/3 is proportional to R(N) 1/3 where N is the number of particles and R their radius . The general features of the time-resolved data resembles those reported by others, for example on study considering the citrate-mediated synthesis of Au NPs. The plot of (Aspr) 1/3 as a function of time can be divided in to three phases : (I) An initial region where (Aspr) 1/3 increases in a superlinear fashion; (II) an intermediate region where (Aspr) 1/3 increases linearly; and (III) a final region where (Aspr) 1/3 exponentially increases and levels off to its final value. For clarity, those phases (I-III) are indicatively illustrated in Figure . Those phases have been attributed to : (I) NP growth via aggregation: Coupled to SAXS measurements, it was established in previous work that the number density of the NP decreases, while the particle size increases in phase I ; (II) no further aggregation occurs, and the particles grow linearly in time via a surface growth reaction; and (III) NP size grows via an autocatalytic growth stage and levels up to its final value. Here, in agreement with previous results , the formation of the Au NP using 20 v.% glycerol (no ethanol) is rather fast in the initial steps of the synthesis, followed by a slow and continuous growth, which is attributed to the redox properties of glycerol and its high viscosity, respectively. Also in agreement with previous reports for the ethanolmediated synthesis (no glycerol), the phases I and II are almost merged which is attributed to the fast formation of the first NPs seeds in absence of stabilizers in the low viscosity solvent together with a slow autocatalytic growth due to the RT process .