An apparatus has been developed to determine the components of the complex shear modulus of viscoelastic liquids and dilute gels over a continuous frequency range from 0.01 to 5 cps by amplitude‐phase shift measurements and from 2.5 to 400 cps by single coil transducer impedance measurements. The temperature range is from −40° to 150°C. The sample is deformed in very small strains with annular pumping geometry, as in the earlier apparatus of Smith, Ferry, and Schremp. Preliminary results on 2.29 and 3.00% solutions of polyvinyl chloride in di‐2‐ethyl hexyl phthalate provide the dynamic storage and loss moduli and the relaxation spectrum as they change during the process of gelation. The moduli of the ungelled solutions, at an early stage of the aggregation process, follow the Zimm theory rather closely, and the local effective viscosity derived therefrom lies between the solvent viscosity and the solution viscosity. The loss compliance of the aged gels is approximately represented by the Bueche theory for cross‐linked networks. However, it is evident that the gels contain a large proportion of sol fraction (polymer species unattached to the network).