The Chemical Abstract Machine (CHAM) is a model inspired by chemical reactions to represent concurrent computations. It uses chemical solutions as states, where molecules interact according to reaction rules. Solutions can be stratified using membranes to enforce local reactions. The paper introduces CHAMs as a model for concurrent processes, demonstrating their ability to capture the semantics of process calculi like TCCS and CCS, and to derive a higher-order concurrent λ-calculus from CHAM concepts. CHAMs are based on the chemical metaphor, where states are chemical solutions, and molecules interact according to reaction rules. Solutions are multisets of molecules, and reactions are multiset rewritings. The model allows for hierarchical programming through membranes, which can encapsulate subsolutions and enable communication between them. The paper illustrates the use of CHAMs by describing the operational semantics of TCCS and CCS. It shows how to extract a higher-order concurrent λ-calculus from CHAM concepts. The model is compared to traditional process calculi, highlighting its ability to handle concurrency through chemical-like interactions, including parallelism, communication, and abstraction. The paper also discusses the handling of a subset of CCS, the semantics of TCCS, and the use of membranes and airlocks to manage restricted communication and hierarchical structures. It presents a formal definition of CHAMs, including transformation rules, and compares them to structural operational semantics (SOS). The paper concludes that CHAMs provide a powerful and flexible model for concurrent computation, with the ability to capture both structural and behavioral aspects of processes.The Chemical Abstract Machine (CHAM) is a model inspired by chemical reactions to represent concurrent computations. It uses chemical solutions as states, where molecules interact according to reaction rules. Solutions can be stratified using membranes to enforce local reactions. The paper introduces CHAMs as a model for concurrent processes, demonstrating their ability to capture the semantics of process calculi like TCCS and CCS, and to derive a higher-order concurrent λ-calculus from CHAM concepts. CHAMs are based on the chemical metaphor, where states are chemical solutions, and molecules interact according to reaction rules. Solutions are multisets of molecules, and reactions are multiset rewritings. The model allows for hierarchical programming through membranes, which can encapsulate subsolutions and enable communication between them. The paper illustrates the use of CHAMs by describing the operational semantics of TCCS and CCS. It shows how to extract a higher-order concurrent λ-calculus from CHAM concepts. The model is compared to traditional process calculi, highlighting its ability to handle concurrency through chemical-like interactions, including parallelism, communication, and abstraction. The paper also discusses the handling of a subset of CCS, the semantics of TCCS, and the use of membranes and airlocks to manage restricted communication and hierarchical structures. It presents a formal definition of CHAMs, including transformation rules, and compares them to structural operational semantics (SOS). The paper concludes that CHAMs provide a powerful and flexible model for concurrent computation, with the ability to capture both structural and behavioral aspects of processes.