I am trying to solve an ODE and PDE and I am having problems coming up with a method for doing so. The PDE is: k1*(dC/dt) = k2*(dC/dx) But I have an ODE that is an expression for dC/dt: dC/dt = k3*C Where k1,k2 and k3 are constants. I planned to use the method of lines to get a solution where C changes with t and x. However, I am having problems dealing with the dC/dt ODE expression. I can use method of lines only on the 1st equation, but that would not take the relationship of the second equation into consideration. If I plug the ODE equation into the PDE, then I will lose the "time" variable. Anyone have any suggestions or tips?