Surface characteristics were studied for particleboards produced from hydro-thermally treated (HTT) and non-treated (NT) wheat stalk (WS). Wood and wheat stalk particles were used as experimental materials. The wheat stalk particles were subjected to HTT at a temperature of 180 °C for 8 minutes in a steam explosion machine. HTT and NT WS particles were added at 10%, 20%, 30%, and 40% to the wood particles. The surface roughness and wettability of the produced panels were determined. The roughness measurements, average roughness (Ra), maximum roughness (Rmax), and mean peak-to-valley height (Rz) were performed using a ﬁne stylus tracing technique. The wetting behavior of the panels was characterized by the contact angle method (goniometer technique). The contact angle (CA) measurements were obtained by using a KSV Cam-101 Scientiﬁc Instrument connected with a digital camera and computer system. Statistical analyses showed signiﬁcant differences in the surface roughness and wettability of the particleboards following hydro-thermal modiﬁcation. The addition of WS to the panels significantly decreased the roughness values. However, all of the HTT groups exhibited higher roughness compared to NT groups. The CA values decreased when the WS content increased. The wettability of the particleboard containing HTT WS particles was improved.