Yarns or fabrics containing cellulose acetate and particularly that form of cellulose acetate known as secondary or acetone soluble acetate are coloured by contacting the yarn or fabric with a composition containing a dyestuff having little or no affinity for cellulose acetate, and a thiocyanate and then subjecting to a steaming process. Dyestuffs used in the present invention comprise in general those having little or no affinity for cellulose acetate, but excluding sulphur dyestuffs and also those dyestuffs which do not yield a coloured product in a preliminary test by padding the yarn or fabric with a dye liquor containing 20-25 per cent of ammonium thiocyanate, drying, steaming and giving an appropriate after treatment. Dyes mentioned as suitable for use in the present invention include the following: Chrysophenine G. 200 per cent, Chlorazol Orange R.N. 125 per cent, Chlorazol fast Yellow 5 G.K. 200 per cent, Chlorazol Orange P.O. 150 per cent, Durazol fast Orange 2 G.S., Durazol fast Brown B.R. 150 per cent, Chlorazol Brown 2 G. 200 per cent, Chlorazol Drab R.H. 125 per cent, Chlorazol fast Red 10 B.S., Durazol Red 2 B. 150 per cent, Chlorazol Scarlet 4 B. 150 per cent, Chlorazol fast Helio 2 R.K.S., Chlorazol Sky Blue F.F. 200 per cent, Durazol fast Blue 8 G.S., Solar Flavine 2 G., Diazamine Bordeana 2 B.L., Trisulphon Brown B., Diazamine Orange R., Direct Green B., Chlorantine fast Yellow 5 G.L.L. 150 per cent, Chlorantine fast Yellow E. 5 G.K. 200 per cent, Diazo fast Yellow 3 G.L.L., Chlorantine fast Orange 2 G.L., Rosanthrene R. 375 per cent, Direct Pink 3 B.N. 200 per cent, Direct brilliant Pink 3 B.C. 250 per cent, Chlorantine fast Blue R.L., Chlorantine fast Brown B.R.L.L. 200 per cent, Diazo Black C.R. 100 per cent, Carbide Black E.N.B., Diazo Phenyl Orange R. 500 per cent, Coomassie Red P.G.P., Coomassie Red R. 150 per cent, Naphthalene Scarlet R.S., Disulphine Blue V.S., Coomassie Milling Scarlet G., Coomassie fast Black G. 125 per cent, Solway Blue P.F.N. 125 per cent, Carbolan Yellow 3 G.S., Coomassie brilliant Blue F.F. 200 per cent, Coomassie Violet R. 150 per cent, Coomassie fast Navy 2 R.N. 140 per cent, Naphthalene Orange G.S., Ponceau 2 R.E. 175 per cent, Roccelline Conc. 120 per cent, Erio Floxene 2 G.L., Erio Floxine 6 B.L., Erio Violet B. 200 per cent, Erio Violet R.L., Erio Viridine B., Erio Glaucine X.S., Erio Green B. 300 per cent, Naphthol Blue Black B.C. 200 per cent, Xylene light Yellow 2 G., Xylene Cyanole F.F. 200 per cent, Xylene fast Green B., Xylene fast Blue B.L., Carmoisine Conc., Alizarine brilliant Green G. Conc., Acid Green G., Durindone Red B.S., Durindone Scarlet 2 B.S., Caledon Red B.N.S., Caledon brilliant Blue 3 G.S., Caledon Yellow G.N. 200 per cent, Caledon Blue G.C.D.S., Caledon jade Green X.N. 200 per cent, Soledon Pink F.F.S., Soledon Orange R. 65 per cent, Soledon golden Yellow R.K.S., Soledon Blue 2 R.C.S., Soledon jade Green X.S., Indigosol O.4B., Indigosol Orange H.R., Indigosol Green A.B., Indigosol O.R., Brenthol C.T., Brenthol F.R., Brenthol B.A., Brenthol P.A. Brenthol O.T., Brenthol A.T., Brenthol A.S., Brenthol F.O., Brenthol M.N., Brenthol A.N., Solochrome Prune A.S., Solochrome Cyanine R. 200 per cent, Chromotartrine C.R., Rapidogen Bordeana R., Magenta, Malachite Green A.S., Acridine Red G., Acridine Flavine R., Victoria Blue B. The following dyestuffs, however, give little or no colour and are unsuitable for the present invention. Chlorantine fast Green 5 B.L.L. 200 per cent, Chlorantine fast Red K., Chlorantine fast Yellow S.L., Direct Green 2 G. Conc., Direct Violet 2 R., Chlorantine fast Orange T.R., Direct Black L., Direct Brown B.B.N., Diazo fast Green 2 G.L. 300 per cent, Chlorazol fast Orange A.G. 125 per cent, Durazol Blue 4 G.S., Tartrazine N. 200 per cent, Solway Blue B. 150 per cent Duridone Brown R.S., Solar Brown P.L., Chloramine New Blue 5 B., Chloramine Maroon B.N., Visco Black N.F.A. The colour may be applied to the yarns according to the present invention by printing as well as dyeing, which may be carried out in the conventional methods. The preferred thiocyanate is amamonium thiocyanate, but sodium, potassium, barium or calcium thiocyanate may also be used. In the printing process the preferred thickener is British Gum. Differential colour effects may be produced by using a mixed fabric of cellulose acetate and another fibre for which the dye used has no affinity. It is stated that by the process of the present invention it is not necessary to remove the weavers' size before dyeing. In examples: (1) a fabric containing cellulose acetate is padded with a dye liquor containing a dyestuff, ammonium thiocyanate and water, dried at 80 DEG C., steamed in a Mather and Platt machine, soaped, rewashed and dried; (2) as in example (1) except that the dye liquor contains British Gum; (3) as in example (2) except that the dye used is an indigosol when the material is after-treated by development in a bath composed of sodium nitrite acidified with sulphuric acid; (4) as in example (2) except that the dye used is a rapidogen when the material is after-treated with an aqueous solution containing acetic and formic acids and Glauber's salts; (5) as in example (2) except that the dyestuff used is an azoic dyestuff when the material is after-treated by coupling with a neutralized diazotized fast colour base such as Brentamine Fast Red B.