We have determined kex and Dchem for (La0.8Sr0.2)0.99Co0.8Ni0.2O3-δ by the use of electrical conductivity relaxation on a dense sample and by applying the ALS model to measured AC impedance spectrum on a porous electrode. Extracting kex and Dchem from the methods resulted in comparable values. kex and Dchem also agreed well with literature values on La0.8Sr0.2CoO3-δ, indicating that nickel substitution does not change the oxygen transport properties. kex of the porous sample was further found to decrease with a five times higher rate than Dchem when measured by using an Electrochemical Impedance Spectroscopy (EIS) over several days.