Abstract: Bis(2-haloacetamido)-compounds for use as linkers to chemically cross-linking multiple thiol groups, and particularly, although not exclusively, the thiol groups of cysteine amino acids in peptide chains are described, along with their use as linking agents and resultant products which comprise antibodies, half-antibodies and antibody fragments having thiol groups bonded to said linkers (e.g. antibody-protein conjugates and antibody-drug conjugates), and methods of making said conjugates and products.