A detailed investigation of the reactions of [RuX3(Eph3)2MeOH](A)(X = Cl or Br; E = P or As) with ligands containing nitrogen (alkyl and aryl cyanides, pyridine, 2,2′-bipyridyl, 1,10-phenanthroline), sulphur (dimethyl sulphoxide, dialkyl sulphides, carbon disulphide, sodium diphenylphosphinodithioate), oxygen (tetrahydrofuran, acetone, nitromethane) and carbon (norbornadiene, 1,5-cyclo-octadiene, carbon monoxide) donor atoms is presented. Five different types of behaviour towards these ligands are exhibited by (A): (1) displacement of methanol giving the ruthenium(III) compounds [RuX3(Eph3)2L], e.g. L = RCN, Me2SO, CS2, CS; (2) displacement of methanol and one Eph3 group giving [RuX3(Eph3)L2], e.g. L2= Me2S, bipy, C5H5N; (3) complete displacement of methanol. Eph3 and X without reduction, e.g.[Ru(S2PPh2)3]; (4) reduction to ruthenium(II) with or without complete displacement of Eph3 groups, e.g.[RuX2L2(Eph3)2](L2= CO, C7H8,RCN) and [RuX2L4](L = C5H5N, Me2SO); (5) reduction to cationic ruthenium(II) compounds in methanol, e.g.[RuCl(PPh3)(N–N)2]Cl [(N–N)= bipy or phen]. Several of these compounds can also be synthesised from [RuX2(PPh3)3]. The compounds are characterised by elemental analyses, molecular weights, e.s.r., and magnetic measurements, and configurations tentatively suggested on the basis of detailed far-i.r. [ruthenium(III)] and 1H n.m.r. [ruthenium(II)] studies. Finally, electronic spectra (50 000–12 000 cm–1) are presented and discussed.