Density (ρ), sound speed (u) and viscosity (η) for an essential amino acid (L-leucine) and a peptide (diglycine) in water and (0.0496, 0.1002 and 0.1498) mol kg−1 mixed aqueous semicarbazide HCl solvent system at five distinct temperatures ranging (293.15 K – 313.15 K) and barometric pressure (101.3 kPa) have been acquired. Varied physicochemical properties like apparent molar parameters (Kϕ,s, Vϕ), hydration number (nH), partial molar parameters (K0ϕ,s, V0ϕ,), viscosity coefficients i.e. Jones Dole and Falkenhagen coefficients, transfer parameters (Vϕ,tro, Kϕ,s,tro, Btr) etc. have been enumerated from the empirically determined data. Moreover, the structure breaking (chaotropic) character of each examined protein subunit has been scrutinized through positive dBdT (temperature dependence of viscosity B-coefficient) values and negative (∂E0ϕ/∂T)p (Hepler’s constant) values. In addition, the cosphere overlap model has been used for a better understanding of assorted predominant molecular interactions in the examined solution mixtures.