Investigations were undertaken on the ethynylation of formaldehyde over a Cu2C2/MgSiO4 in a slurry reactor to study the reaction kineics. The results show that this catalyst is highly selective to the main product 1,4-butynediol. It was found that the reaction rate is first order with respect to catalyst loading and zeroeth order in acetylene partial pressure at above 1.0 kg/cm2. The activation energy was found to be 51.88 kJ/mol ensuring that the rate controlling step is a surface reaction. We chose to use a mechanistic model to explain our experimental data. We postulated a reaction mechanism in which reactants are adsorbed on different active sites respectively. According to this , the following rate expression of Langmuir-Hinshelwood type were obtained for the ethynylation of formaldehyde at 363 K: -r(F) = 2.34*10(-3)WC(F)\1 + 0.47C(F) (kmol/m3 h) We also found that the ethynylation reaction can be expressed with a simple empirical power law model with a reaction order of 0.59 with respect to formaldehyde.