Initial results are reported from lower hybrid wave heating experiments carried out on the MIT Alcator C and Versator II tokamaks. In the Alcator C experiments a 4 waveguide array, with internally brazed ceramic windows has been used to inject 160 kW of microwave power at 4.6 GHz into the plasma with n0 less than or equal to 1 x 1015 cm−3, and B0 less than or equal to 12 T. An RF power density of 8 kW/cm2 has been transmitted into the plasma without RF breakdown. RF coupling studies show optimal coupling (R less than or equal to 10%) when the local density at the waveguide mouth is 25 to 50 times overdense. Initial heating experiments show an ion tail formation in hydrogen discharge peaking at a density of anti n approx. = 2.7 x 1014 cm−3 at B = 8.9 T, and bulk ion heating at a density of anti n approx. = 1.5 x 1014 c−3 at B approx. = 11 T. Evidence of RF current enhancement has been observed at a density of n approx. = 3 x 1013 cm−3. In the Versator II tokamak initial ion heating studies have been carried out using an 800 MHz, 140 kW klystron. With 50 kW of net RF power injected through a 4 waveguide grill at B = 1.3 T and anti n = 2.5 x 1013 cm−3, Doppler broadening of the OVII and NVI lines shows a .delta.T/sub i/ = 50 eV rise in the bulk ion temperature. A significant RF produced ion tail is also observed by charge exchange analysis. We have succeeded in combining a toroidal ray-tracing code and a 1-D transport code to study the heating density bands and heating efficiencies.