Experiments and simulation results are presented in this dissertation that explore the fundamental multiphase burning characteristics of selected biofuels and their blends with transportation fuels, gasoline surrogates, and n-propylbenzene which is an aromatic hydrocarbon representative of this class found in transportation fuels. The configuration employed is an isolated droplet burning in an environment designed to promote spherical symmetry during combustion. The systems investigated were heptane/iso-butanol, n-propylbenzene, four-component (S4), five-component (S5), and six-component (S6) surrogates for a gasoline certification fuel (indolene), indolene/iso-butanol and S5/iso-butanol blends. The parameters were the initial droplet diameter (0.6 mm ≤ D0 ≤ 5.8 mm) for the n-propylbenzene study and fractional amount of iso-butanol for the others with a fixed initial droplet diameter at 0.6 mm.The experimental results showed that the S5 best matched indolene among three selected surrogates. The burning rates, flame standoff ratio (FSR) and soot shell standoff ratio (SSR) of indolene/iso-butanol and S5/iso-butanol were found to be nearly identical. The experiment results also showed that increasing iso-butanol fraction in the mixtures significantly reduced soot propensity. The burning behavior of n-propylbenzene exhibited a high soot propensity, and extinction was observed for large droplets (D₀ ≥ 3.2 mm). The experimental results also showed that droplet burning rates decreased as the droplet size increased due to greater radiative losses from larger droplets flame. Detailed combustion simulations were conducted using the OPENSMOKE++ framework, incorporating models of both soot formation and fuel mixture effects. Simulations of heptane/iso-butanol, S5, S5/iso-butanol and n-propylbenzene droplet, flame and soot shell diameters were well predicted in the simulations. Flame diameters were predicted using definitions of the flame based on the highest gas temperature or the maximum OH concentration in the computational field. Soot shells were predicted to coincide with the location of maximum soot volume fraction. The role of radiation on burning was also investigated numerically. As the initial droplet diameter increased, the burning rates decreased, due to enhanced radiative heat losses from the larger droplets flame, which also sometimes led to flame extinction. The significance of the results lies in the successful execution of the experiments to provide a database for different complex fuel systems. These results revealed the impact of iso-butanol as an additive in gasoline and the soot formation dynamics of n-propylbenzene from both experimental and numerical perspectives. The methodologies developed provide a deeper understanding of fuel combustion characteristics across different fuel types. Future research can build on the results presented to further explore next-generation biofuels and their blends with transportation fuels using the methodology described in this thesis, ultimately contributing to advances in combustion science, energy security and climate change mitigation.