Experimental hydrate equilibrium data and thermodynamic modelling of isopentane and 2,2-dimethylpentane (2,2-DMP) are presented. Both compounds are reported to form structure-H gas hydrates in the presence of a help gas. Hydrate dissociation data for isopentane and 2,2-DMP in their binaries and ternaries with methane and/or nitrogen are measured and successfully modelled using an equation of state-based thermodynamic model. Indication of a change in the stable hydrate structure (structure-H to structure-I) for isopentane and 2,2-DMP in their binaries with methane at higher temperatures is also discussed.