The application of response surface methodology was highlighted to predict and optimize the percentage of dilution of iron-based hardfaced surface produced by the PTA (plasma transferred arc welding) process.The experi- ments were conducted based on five-factor five-level central composite rotatable design with full replication technique and a mathematical model was developed using response surface methodology.Furthermore,the response surface methodology was also used to optimize the process parameters that yielded the lowest percentage of dilution. The application of response surface methodology was highlighted to predict and optimize the percentage of dilution of iron-based hardfaced surface produced by the PTA (plasma transferred arc welding) process.The experimenters were conducted based on five-factor five-level central composite rotatable design with full replication technique and a mathematical model was developed using response surface methodology. Still more, the response surface methodology was also used to optimize the process parameters that yielded the lowest percentage of dilution.