This　paper　reported　a　study　on　the　heat　transfer　in　solidification　of　phase　change　materials　(PCMs)　embedded　in　metal　foam.　Heat　transfer　enhancement　techniques　are　addressed　in　solidification　including　the　insertion　of　pin　fins　and　gradient　design　of　pore　parameters.　Numerical　models　to　describe　the　transient　phase　change　heat　transfer　are　established　through　the　volume-averaged　theory.　One-temperature　model　is　accounted　for　under　the　core　assumption　of　local　thermal　equilibrium　state.　An　experimental　test　rig　is　designed　and　established　to　verify　the　feasibility　of　the　built　numerical　models　by　means　of　comparing　solidification　fronts　and　temperatures　at　PCM.　The　effects　of　gradients　in　parent　materials,　porosity　and　pore　density　for　metal　foam　upon　solidification　behavior　in　metal　foam　and　pin　fin-metal　foam　hybrid　structures　are　quantified.　The　contribution　of　local　natural　convection　to　the　solidification　behavior　is　justified　and　found　this　effect　can　be　safely　neglected　for　simulation　on　solidification　in　metal　foam.　Results　demonstrate　that　the　insertion　of　pin　fins　notably　improve　the　solidification　in　metal　foam　regardless　of　gradient　in　pore　parameters.　The　gradient　in　porosity　rather　than　parent　materials　for　the　pin　fin-metal　foam　hybrid　structures　can　further　improve　the　solidification　rate.　As　for　metal　foam,　both　gradient　in　parent　materials　and　graded　porosity　can　significantly　promote　the　solidification.　The　best　heat　transfer　structure　is　recommend　to　be　a　pin　fin-metal　foam　hybrid　structure　with　gradient　in　metal　foam　porosity,　outperforming　other　competing　heat　transfer　techniques　including　pin　fins　or　metal　foam.