In this work, measurements of the critical parameters for cis-1,1,1,4,4,4-hexafluoro-2-butene (HFO-1336mzz(Z)) were carried out by the meniscus disappearance method. Menisci were observed along five isochoric lines in the density range from 465 kg center dot m(-3) to 536 kg center dot m(-3), that is, near the critical density reported in our previous work. Critical opalescence was observed along all isochoric lines. The critical density was determined as the density at which the meniscus remained fixed with decreasing temperature. The critical temperature and critical pressure were determined from the observation of the meniscus disappearance with temperature increasing in 0.01 K intervals. The critical density, critical temperature, and critical pressure of HFO-1336mzz(Z) were determined to be 507 +/- 5 kg center dot m(-3), 444.50 +/- 0.03 K, and 2895 +/- 6 kPa, respectively.