This chapter focuses on the development of synthetic routes to introduce well-defined porosity into hydrothermal carbons. It introduces and discusses various synthetic routes towards porous hydrothermal carbonization (HTC)-derived materials or composites, focusing on the synthesis of different pore systems and morphologies directed by the presence of various structure-directing agents. Attention is given to the utilization of naturally occurring biocomposites and their use in the preparation of porous HTC-derived materials. The methods presented in the chapter allow tailoring of the final structure via the tools of colloid and polymer science, leading to selectable material morphology for a wide range of applications. Aerogels are known in a great variety of compositions and are used in numerous high-end applications, including chromatography, adsorption, separation, gas storage, detectors, heat insulation, and as supports and ion exchange materials.