High pressure serves as a powerful thermodynamic variable for tailoring the physical behavior of nanomaterials, often revealing novel mechanical, structural, and thermophysical responses beyond bulk limits. This Special Issue, Nanomaterials under High Pressure, focuses on advancing the fundamental and predictive understanding of pressure-driven phenomena in nanoscale systems. Emphasis is placed on theoretical, analytical, and semi-empirical frameworks, particularly the formulation and validation of equations of state, finite-strain approaches, and thermodynamic models to evaluate elastic constants, bulk modulus, Grüneisen parameter, Debye temperature, phase stability, and melting characteristics under extreme compression. The Issue features original research articles, short communications, and authoritative review papers addressing nanometals, oxides, chalcogenides, superconductors, and smart materials, supported by numerical simulations and complementary experimental insights. Collectively, these contributions aim to establish robust structure–property–pressure relationships and guide future high-pressure nanomaterials research.

• Nanomaterials
• High pressure
• Equation of state (EOS)
• Thermoelastic properties
• Finite strain theory
• Grüneisen parameter
• Bulk modulus
• Debye temperature
• Phase stability
• Extreme compression
• Size and shape effects
• Theoretical and semi-empirical modeling