Density ρ, sound velocity u, surface tension γ, viscosity η and conductance for (0.01 to 0.10mol·kg−1) alkyltrimethyl ammonium bromide (CnTAB, DTAB n=12, TDTAB n=14 and HDTAB n=16) with (0.999millimol·kg−1) quercetin, apigenin and naringenin flavonoids and (2g·kg−1) bovine serum albumin (BSA) in aqueous 10% DMSO (w/w) at T=298.15, 303.15, 308.15K and p=0.1MPa are reported. The ρ, u, γ and η data have calculated apparent molar volume Vϕ, isentropic compressibility ks, apparent molar isentropic compressibility ks,ϕ, intrinsic viscosity [η] and activation energy E∗, to determine the contribution of methylene (CH2) groups of CnTAB. The γ, surface excess concentration Гmax, molecular surface area Amin, hydrodynamic radius Rh, hydrodynamic volume Vh, friccohesity σ and k on increasing CnTAB alkyl chain length infer higher dispersion. Hydrophobicity of BSA in aq-DMSO with flavonoids is as quercetin<apigenin<naringenin, on the weakening of cohesive forces and increasing intermolecular forces with a decrease in surface tension and increase in viscosity for homogenization. The CnTAB develops stronger electrostatic and hydrophobic interactions with BSA and flavonoids denature native BSA structure. Increasing alkyl chain length has catalysed BSA with flavonoids on mutual interactions strengthening their interacting activities, proven with higher η and lower γ values.