The demand for multifunctional porous materials in advanced technological applications has intensified, pushing the boundaries beyond what conventional porous materials can achieve. This necessitates the creation of novel materials that can seamlessly integrate diverse functions. In this context, the drive to enhance foam efficiency is spurred by the need to elevate fundamental characteristics and extend the applicability of foams to meet the intricate demands of modern technologies. This pursuit is motivated by the aspiration to uncover new levels of functionality and performance, enabling foams to address challenges that conventional materials struggle to overcome. In response to this challenge, extensive efforts have been made to enhance the properties of foams, particularly, open-pore foams. These attempts encompass a range of approaches, from optimizing manufacturing methodologies to incorporating diverse materials, all aimed at meeting multifaceted requirements across many applications. This thesis study multifunctional porous materials known as Guefoam with defined porosity using metal, polymer and ceramic precursors. The multifunctional Guefoam is an open-cell foam (host foam) that contains guest phases in porous cavities (no chemical or physical interaction), where the cavities contain other phases that provide specific functionalities and allow flow to pass through. The focus is on investigating the ability of the guest phase to enhance heat transfer dissipation of metal Guefoams and to remove waterborne microorganisms within the polymer Guefoams. In thermal management, two types of foams were fabricated using the replication method: conventional aluminum foams and aluminum Guefoams (containing guest phases). Additionally, tin foam and Guefoam were fabricated for comparison in properties to assess the effect of changing the matrix. Open-pore foams and Guefoams were fabricated using two types of preforms: NaCl spheres and NaCl-containing steel spheres as guest phases, respectively. Two groups of samples were developed with different average sizes of pore interconnecting windows by applying two different pressures. They are classified as samples with large windows with an average size of 0.66-0.73 mm (foam 1, Guefoam 1 (containing 2 mm steel spheres), and Guefoam 2 (containing 3 mm steel spheres)), and samples with small windows of an average size of 1.29-1.31 mm (foam 2, Guefoam 3 (containing 2 mm steel spheres), and Guefoam 4 (containing 3 mm steel spheres)), fabricated under infiltration pressures of 0.5 bar and 1.5 bar, respectively. The size of pore interconnecting windows, guest sizes, porosity, and the sample length structure were varied to observe their effects on the functional properties of the samples and to determine the most optimal structure for the desired application. The structural parameter characterization porosity, metal volume fraction, size distribution of pore interconnecting windows and guest occupation (GO) was correlated to the fluid flow behaviors of samples which were evaluated through measurements of pressure drop, permeability, and the form drag coefficient. Additionally, these structural parameters were also correlated with the thermal behaviors of the samples, including power dissipation density and thermal conductivity. In pathogen microorganism capture application, foam and Guefoam were fabricated with ceramic and polymer liquid precursors via the replication method. This method allows to produce porous metals with homogenous interconnecting windows and provides high control over pore shape, size, and size distribution. However, the NaCl template cannot be utilized to produce foams with ceramic and polymer liquid precursors since they tend to completely (or partially) dissolve the NaCl during processing and wet the NaCl particles, respectively, and, as a result, leave no interconnecting windows between pores. To address this limitation, a modification to the replication method is proposed. This modification involves the incorporation of paraffin as a secondary templating agent that coats the NaCl particles. After heat treatment, the paraffin creates binding collars between the NaCl particles that ensure the formation of interconnecting windows after the double template removal. The fabricated Guefoams with different sizes of pore interconnecting windows and iodine-impregnated activated carbon (I-AC) guest phases were tested for Escherichia coli removal. The size of pore interconnecting window determines the permeability and pressure drop in these materials, and thus, their energy efficiency. By precisely controlling the number and the size of pore interconnecting windows, the permeability and interaction between the guest phase and bacteria-bearing water could be optimized. Designing materials with interconnecting windows ranging from 0.40-0.83 mm, exhibit highly permeable properties for efficient water filtration. Consequently, the developed materials hold great potential for future advancements in energy-efficient and functionally effective filter systems. In this thesis study, a new family of open-pore foams called Guefoam (an acronym for guest-containing foam) was successfully fabricated via the replication method using different matrices, cement, resin epoxy, aluminum and tin. The structural morphology, including porosity, guest size, pore size, size of pore interconnecting window, were all controlled. Their effects on the functional properties of foam and Guefoam materials were investigated by numerous characterization studies. The focus has been directed towards improving foam materials functionality by incorporating different guest phases. This endeavor in the domain of material design and application emanates with an extraordinary potential to profoundly influence and enrich the scientific community. As the frontiers of possibility continue to expand, this study illuminating the trajectory of Guefoam materials towards advancements that are poised to undoubtedly shape a brighter and more promising future. / Financial support from the Spanish Agencia Estatal de Investigación (AEI), the Spanish Ministry of Science and Innovation, and the European Union for grants PDC2021-121617-C21, and the Conselleria d'Innovació, Universitats, Ciència, i Societat Digital of the Generalitat Valenciana through grant GVA-COVID19/2021/097.